Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 837 insertions, 0 deletions

diff --git a/lib/xz/xz_dec_stream.c b/lib/xz/xz_dec_stream.c
new file mode 100644
index 000000000..683570b93
--- /dev/null
+++ b/lib/xz/xz_dec_stream.c
@@ -0,0 +1,837 @@
+/*
+ * .xz Stream decoder
+ *
+ * Author: Lasse Collin <lasse.collin@tukaani.org>
+ *
+ * This file has been put into the public domain.
+ * You can do whatever you want with this file.
+ */
+
+#include "xz_private.h"
+#include "xz_stream.h"
+
+/* Hash used to validate the Index field */
+struct xz_dec_hash {
+	vli_type unpadded;
+	vli_type uncompressed;
+	uint32_t crc32;
+};
+
+struct xz_dec {
+	/* Position in dec_main() */
+	enum {
+		SEQ_STREAM_HEADER,
+		SEQ_BLOCK_START,
+		SEQ_BLOCK_HEADER,
+		SEQ_BLOCK_UNCOMPRESS,
+		SEQ_BLOCK_PADDING,
+		SEQ_BLOCK_CHECK,
+		SEQ_INDEX,
+		SEQ_INDEX_PADDING,
+		SEQ_INDEX_CRC32,
+		SEQ_STREAM_FOOTER
+	} sequence;
+
+	/* Position in variable-length integers and Check fields */
+	uint32_t pos;
+
+	/* Variable-length integer decoded by dec_vli() */
+	vli_type vli;
+
+	/* Saved in_pos and out_pos */
+	size_t in_start;
+	size_t out_start;
+
+	/* CRC32 value in Block or Index */
+	uint32_t crc32;
+
+	/* Type of the integrity check calculated from uncompressed data */
+	enum xz_check check_type;
+
+	/* Operation mode */
+	enum xz_mode mode;
+
+	/*
+	 * True if the next call to xz_dec_run() is allowed to return
+	 * XZ_BUF_ERROR.
+	 */
+	bool allow_buf_error;
+
+	/* Information stored in Block Header */
+	struct {
+		/*
+		 * Value stored in the Compressed Size field, or
+		 * VLI_UNKNOWN if Compressed Size is not present.
+		 */
+		vli_type compressed;
+
+		/*
+		 * Value stored in the Uncompressed Size field, or
+		 * VLI_UNKNOWN if Uncompressed Size is not present.
+		 */
+		vli_type uncompressed;
+
+		/* Size of the Block Header field */
+		uint32_t size;
+	} block_header;
+
+	/* Information collected when decoding Blocks */
+	struct {
+		/* Observed compressed size of the current Block */
+		vli_type compressed;
+
+		/* Observed uncompressed size of the current Block */
+		vli_type uncompressed;
+
+		/* Number of Blocks decoded so far */
+		vli_type count;
+
+		/*
+		 * Hash calculated from the Block sizes. This is used to
+		 * validate the Index field.
+		 */
+		struct xz_dec_hash hash;
+	} block;
+
+	/* Variables needed when verifying the Index field */
+	struct {
+		/* Position in dec_index() */
+		enum {
+			SEQ_INDEX_COUNT,
+			SEQ_INDEX_UNPADDED,
+			SEQ_INDEX_UNCOMPRESSED
+		} sequence;
+
+		/* Size of the Index in bytes */
+		vli_type size;
+
+		/* Number of Records (matches block.count in valid files) */
+		vli_type count;
+
+		/*
+		 * Hash calculated from the Records (matches block.hash in
+		 * valid files).
+		 */
+		struct xz_dec_hash hash;
+	} index;
+
+	/*
+	 * Temporary buffer needed to hold Stream Header, Block Header,
+	 * and Stream Footer. The Block Header is the biggest (1 KiB)
+	 * so we reserve space according to that. buf[] has to be aligned
+	 * to a multiple of four bytes; the size_t variables before it
+	 * should guarantee this.
+	 */
+	struct {
+		size_t pos;
+		size_t size;
+		uint8_t buf[1024];
+	} temp;
+
+	struct xz_dec_lzma2 *lzma2;
+
+#ifdef XZ_DEC_BCJ
+	struct xz_dec_bcj *bcj;
+	bool bcj_active;
+#endif
+};
+
+#ifdef XZ_DEC_ANY_CHECK
+/* Sizes of the Check field with different Check IDs */
+static const uint8_t check_sizes[16] = {
+	0,
+	4, 4, 4,
+	8, 8, 8,
+	16, 16, 16,
+	32, 32, 32,
+	64, 64, 64
+};
+#endif
+
+/*
+ * Fill s->temp by copying data starting from b->in[b->in_pos]. Caller
+ * must have set s->temp.pos to indicate how much data we are supposed
+ * to copy into s->temp.buf. Return true once s->temp.pos has reached
+ * s->temp.size.
+ */
+static bool fill_temp(struct xz_dec *s, struct xz_buf *b)
+{
+	size_t copy_size = min_t(size_t,
+			b->in_size - b->in_pos, s->temp.size - s->temp.pos);
+
+	memcpy(s->temp.buf + s->temp.pos, b->in + b->in_pos, copy_size);
+	b->in_pos += copy_size;
+	s->temp.pos += copy_size;
+
+	if (s->temp.pos == s->temp.size) {
+		s->temp.pos = 0;
+		return true;
+	}
+
+	return false;
+}
+
+/* Decode a variable-length integer (little-endian base-128 encoding) */
+static enum xz_ret dec_vli(struct xz_dec *s, const uint8_t *in,
+			   size_t *in_pos, size_t in_size)
+{
+	uint8_t byte;
+
+	if (s->pos == 0)
+		s->vli = 0;
+
+	while (*in_pos < in_size) {
+		byte = in[*in_pos];
+		++*in_pos;
+
+		s->vli |= (vli_type)(byte & 0x7F) << s->pos;
+
+		if ((byte & 0x80) == 0) {
+			/* Don't allow non-minimal encodings. */
+			if (byte == 0 && s->pos != 0)
+				return XZ_DATA_ERROR;
+
+			s->pos = 0;
+			return XZ_STREAM_END;
+		}
+
+		s->pos += 7;
+		if (s->pos == 7 * VLI_BYTES_MAX)
+			return XZ_DATA_ERROR;
+	}
+
+	return XZ_OK;
+}
+
+/*
+ * Decode the Compressed Data field from a Block. Update and validate
+ * the observed compressed and uncompressed sizes of the Block so that
+ * they don't exceed the values possibly stored in the Block Header
+ * (validation assumes that no integer overflow occurs, since vli_type
+ * is normally uint64_t). Update the CRC32 if presence of the CRC32
+ * field was indicated in Stream Header.
+ *
+ * Once the decoding is finished, validate that the observed sizes match
+ * the sizes possibly stored in the Block Header. Update the hash and
+ * Block count, which are later used to validate the Index field.
+ */
+static enum xz_ret dec_block(struct xz_dec *s, struct xz_buf *b)
+{
+	enum xz_ret ret;
+
+	s->in_start = b->in_pos;
+	s->out_start = b->out_pos;
+
+#ifdef XZ_DEC_BCJ
+	if (s->bcj_active)
+		ret = xz_dec_bcj_run(s->bcj, s->lzma2, b);
+	else
+#endif
+		ret = xz_dec_lzma2_run(s->lzma2, b);
+
+	s->block.compressed += b->in_pos - s->in_start;
+	s->block.uncompressed += b->out_pos - s->out_start;
+
+	/*
+	 * There is no need to separately check for VLI_UNKNOWN, since
+	 * the observed sizes are always smaller than VLI_UNKNOWN.
+	 */
+	if (s->block.compressed > s->block_header.compressed
+			|| s->block.uncompressed
+				> s->block_header.uncompressed)
+		return XZ_DATA_ERROR;
+
+	if (s->check_type == XZ_CHECK_CRC32)
+		s->crc32 = xz_crc32(b->out + s->out_start,
+				b->out_pos - s->out_start, s->crc32);
+
+	if (ret == XZ_STREAM_END) {
+		if (s->block_header.compressed != VLI_UNKNOWN
+				&& s->block_header.compressed
+					!= s->block.compressed)
+			return XZ_DATA_ERROR;
+
+		if (s->block_header.uncompressed != VLI_UNKNOWN
+				&& s->block_header.uncompressed
+					!= s->block.uncompressed)
+			return XZ_DATA_ERROR;
+
+		s->block.hash.unpadded += s->block_header.size
+				+ s->block.compressed;
+
+#ifdef XZ_DEC_ANY_CHECK
+		s->block.hash.unpadded += check_sizes[s->check_type];
+#else
+		if (s->check_type == XZ_CHECK_CRC32)
+			s->block.hash.unpadded += 4;
+#endif
+
+		s->block.hash.uncompressed += s->block.uncompressed;
+		s->block.hash.crc32 = xz_crc32(
+				(const uint8_t *)&s->block.hash,
+				sizeof(s->block.hash), s->block.hash.crc32);
+
+		++s->block.count;
+	}
+
+	return ret;
+}
+
+/* Update the Index size and the CRC32 value. */
+static void index_update(struct xz_dec *s, const struct xz_buf *b)
+{
+	size_t in_used = b->in_pos - s->in_start;
+	s->index.size += in_used;
+	s->crc32 = xz_crc32(b->in + s->in_start, in_used, s->crc32);
+}
+
+/*
+ * Decode the Number of Records, Unpadded Size, and Uncompressed Size
+ * fields from the Index field. That is, Index Padding and CRC32 are not
+ * decoded by this function.
+ *
+ * This can return XZ_OK (more input needed), XZ_STREAM_END (everything
+ * successfully decoded), or XZ_DATA_ERROR (input is corrupt).
+ */
+static enum xz_ret dec_index(struct xz_dec *s, struct xz_buf *b)
+{
+	enum xz_ret ret;
+
+	do {
+		ret = dec_vli(s, b->in, &b->in_pos, b->in_size);
+		if (ret != XZ_STREAM_END) {
+			index_update(s, b);
+			return ret;
+		}
+
+		switch (s->index.sequence) {
+		case SEQ_INDEX_COUNT:
+			s->index.count = s->vli;
+
+			/*
+			 * Validate that the Number of Records field
+			 * indicates the same number of Records as
+			 * there were Blocks in the Stream.
+			 */
+			if (s->index.count != s->block.count)
+				return XZ_DATA_ERROR;
+
+			s->index.sequence = SEQ_INDEX_UNPADDED;
+			break;
+
+		case SEQ_INDEX_UNPADDED:
+			s->index.hash.unpadded += s->vli;
+			s->index.sequence = SEQ_INDEX_UNCOMPRESSED;
+			break;
+
+		case SEQ_INDEX_UNCOMPRESSED:
+			s->index.hash.uncompressed += s->vli;
+			s->index.hash.crc32 = xz_crc32(
+					(const uint8_t *)&s->index.hash,
+					sizeof(s->index.hash),
+					s->index.hash.crc32);
+			--s->index.count;
+			s->index.sequence = SEQ_INDEX_UNPADDED;
+			break;
+		}
+	} while (s->index.count > 0);
+
+	return XZ_STREAM_END;
+}
+
+/*
+ * Validate that the next four input bytes match the value of s->crc32.
+ * s->pos must be zero when starting to validate the first byte.
+ */
+static enum xz_ret crc32_validate(struct xz_dec *s, struct xz_buf *b)
+{
+	do {
+		if (b->in_pos == b->in_size)
+			return XZ_OK;
+
+		if (((s->crc32 >> s->pos) & 0xFF) != b->in[b->in_pos++])
+			return XZ_DATA_ERROR;
+
+		s->pos += 8;
+
+	} while (s->pos < 32);
+
+	s->crc32 = 0;
+	s->pos = 0;
+
+	return XZ_STREAM_END;
+}
+
+#ifdef XZ_DEC_ANY_CHECK
+/*
+ * Skip over the Check field when the Check ID is not supported.
+ * Returns true once the whole Check field has been skipped over.
+ */
+static bool check_skip(struct xz_dec *s, struct xz_buf *b)
+{
+	while (s->pos < check_sizes[s->check_type]) {
+		if (b->in_pos == b->in_size)
+			return false;
+
+		++b->in_pos;
+		++s->pos;
+	}
+
+	s->pos = 0;
+
+	return true;
+}
+#endif
+
+/* Decode the Stream Header field (the first 12 bytes of the .xz Stream). */
+static enum xz_ret dec_stream_header(struct xz_dec *s)
+{
+	if (!memeq(s->temp.buf, HEADER_MAGIC, HEADER_MAGIC_SIZE))
+		return XZ_FORMAT_ERROR;
+
+	if (xz_crc32(s->temp.buf + HEADER_MAGIC_SIZE, 2, 0)
+			!= get_le32(s->temp.buf + HEADER_MAGIC_SIZE + 2))
+		return XZ_DATA_ERROR;
+
+	if (s->temp.buf[HEADER_MAGIC_SIZE] != 0)
+		return XZ_OPTIONS_ERROR;
+
+	/*
+	 * Of integrity checks, we support only none (Check ID = 0) and
+	 * CRC32 (Check ID = 1). However, if XZ_DEC_ANY_CHECK is defined,
+	 * we will accept other check types too, but then the check won't
+	 * be verified and a warning (XZ_UNSUPPORTED_CHECK) will be given.
+	 */
+	if (s->temp.buf[HEADER_MAGIC_SIZE + 1] > XZ_CHECK_MAX)
+		return XZ_OPTIONS_ERROR;
+
+	s->check_type = s->temp.buf[HEADER_MAGIC_SIZE + 1];
+
+#ifdef XZ_DEC_ANY_CHECK
+	if (s->check_type > XZ_CHECK_CRC32)
+		return XZ_UNSUPPORTED_CHECK;
+#else
+	if (s->check_type > XZ_CHECK_CRC32)
+		return XZ_OPTIONS_ERROR;
+#endif
+
+	return XZ_OK;
+}
+
+/* Decode the Stream Footer field (the last 12 bytes of the .xz Stream) */
+static enum xz_ret dec_stream_footer(struct xz_dec *s)
+{
+	if (!memeq(s->temp.buf + 10, FOOTER_MAGIC, FOOTER_MAGIC_SIZE))
+		return XZ_DATA_ERROR;
+
+	if (xz_crc32(s->temp.buf + 4, 6, 0) != get_le32(s->temp.buf))
+		return XZ_DATA_ERROR;
+
+	/*
+	 * Validate Backward Size. Note that we never added the size of the
+	 * Index CRC32 field to s->index.size, thus we use s->index.size / 4
+	 * instead of s->index.size / 4 - 1.
+	 */
+	if ((s->index.size >> 2) != get_le32(s->temp.buf + 4))
+		return XZ_DATA_ERROR;
+
+	if (s->temp.buf[8] != 0 || s->temp.buf[9] != s->check_type)
+		return XZ_DATA_ERROR;
+
+	/*
+	 * Use XZ_STREAM_END instead of XZ_OK to be more convenient
+	 * for the caller.
+	 */
+	return XZ_STREAM_END;
+}
+
+/* Decode the Block Header and initialize the filter chain. */
+static enum xz_ret dec_block_header(struct xz_dec *s)
+{
+	enum xz_ret ret;
+
+	/*
+	 * Validate the CRC32. We know that the temp buffer is at least
+	 * eight bytes so this is safe.
+	 */
+	s->temp.size -= 4;
+	if (xz_crc32(s->temp.buf, s->temp.size, 0)
+			!= get_le32(s->temp.buf + s->temp.size))
+		return XZ_DATA_ERROR;
+
+	s->temp.pos = 2;
+
+	/*
+	 * Catch unsupported Block Flags. We support only one or two filters
+	 * in the chain, so we catch that with the same test.
+	 */
+#ifdef XZ_DEC_BCJ
+	if (s->temp.buf[1] & 0x3E)
+#else
+	if (s->temp.buf[1] & 0x3F)
+#endif
+		return XZ_OPTIONS_ERROR;
+
+	/* Compressed Size */
+	if (s->temp.buf[1] & 0x40) {
+		if (dec_vli(s, s->temp.buf, &s->temp.pos, s->temp.size)
+					!= XZ_STREAM_END)
+			return XZ_DATA_ERROR;
+
+		s->block_header.compressed = s->vli;
+	} else {
+		s->block_header.compressed = VLI_UNKNOWN;
+	}
+
+	/* Uncompressed Size */
+	if (s->temp.buf[1] & 0x80) {
+		if (dec_vli(s, s->temp.buf, &s->temp.pos, s->temp.size)
+				!= XZ_STREAM_END)
+			return XZ_DATA_ERROR;
+
+		s->block_header.uncompressed = s->vli;
+	} else {
+		s->block_header.uncompressed = VLI_UNKNOWN;
+	}
+
+#ifdef XZ_DEC_BCJ
+	/* If there are two filters, the first one must be a BCJ filter. */
+	s->bcj_active = s->temp.buf[1] & 0x01;
+	if (s->bcj_active) {
+		if (s->temp.size - s->temp.pos < 2)
+			return XZ_OPTIONS_ERROR;
+
+		ret = xz_dec_bcj_reset(s->bcj, s->temp.buf[s->temp.pos++]);
+		if (ret != XZ_OK)
+			return ret;
+
+		/*
+		 * We don't support custom start offset,
+		 * so Size of Properties must be zero.
+		 */
+		if (s->temp.buf[s->temp.pos++] != 0x00)
+			return XZ_OPTIONS_ERROR;
+	}
+#endif
+
+	/* Valid Filter Flags always take at least two bytes. */
+	if (s->temp.size - s->temp.pos < 2)
+		return XZ_DATA_ERROR;
+
+	/* Filter ID = LZMA2 */
+	if (s->temp.buf[s->temp.pos++] != 0x21)
+		return XZ_OPTIONS_ERROR;
+
+	/* Size of Properties = 1-byte Filter Properties */
+	if (s->temp.buf[s->temp.pos++] != 0x01)
+		return XZ_OPTIONS_ERROR;
+
+	/* Filter Properties contains LZMA2 dictionary size. */
+	if (s->temp.size - s->temp.pos < 1)
+		return XZ_DATA_ERROR;
+
+	ret = xz_dec_lzma2_reset(s->lzma2, s->temp.buf[s->temp.pos++]);
+	if (ret != XZ_OK)
+		return ret;
+
+	/* The rest must be Header Padding. */
+	while (s->temp.pos < s->temp.size)
+		if (s->temp.buf[s->temp.pos++] != 0x00)
+			return XZ_OPTIONS_ERROR;
+
+	s->temp.pos = 0;
+	s->block.compressed = 0;
+	s->block.uncompressed = 0;
+
+	return XZ_OK;
+}
+
+static enum xz_ret dec_main(struct xz_dec *s, struct xz_buf *b)
+{
+	enum xz_ret ret;
+
+	/*
+	 * Store the start position for the case when we are in the middle
+	 * of the Index field.
+	 */
+	s->in_start = b->in_pos;
+
+	while (true) {
+		switch (s->sequence) {
+		case SEQ_STREAM_HEADER:
+			/*
+			 * Stream Header is copied to s->temp, and then
+			 * decoded from there. This way if the caller
+			 * gives us only little input at a time, we can
+			 * still keep the Stream Header decoding code
+			 * simple. Similar approach is used in many places
+			 * in this file.
+			 */
+			if (!fill_temp(s, b))
+				return XZ_OK;
+
+			/*
+			 * If dec_stream_header() returns
+			 * XZ_UNSUPPORTED_CHECK, it is still possible
+			 * to continue decoding if working in multi-call
+			 * mode. Thus, update s->sequence before calling
+			 * dec_stream_header().
+			 */
+			s->sequence = SEQ_BLOCK_START;
+
+			ret = dec_stream_header(s);
+			if (ret != XZ_OK)
+				return ret;
+
+			fallthrough;
+
+		case SEQ_BLOCK_START:
+			/* We need one byte of input to continue. */
+			if (b->in_pos == b->in_size)
+				return XZ_OK;
+
+			/* See if this is the beginning of the Index field. */
+			if (b->in[b->in_pos] == 0) {
+				s->in_start = b->in_pos++;
+				s->sequence = SEQ_INDEX;
+				break;
+			}
+
+			/*
+			 * Calculate the size of the Block Header and
+			 * prepare to decode it.
+			 */
+			s->block_header.size
+				= ((uint32_t)b->in[b->in_pos] + 1) * 4;
+
+			s->temp.size = s->block_header.size;
+			s->temp.pos = 0;
+			s->sequence = SEQ_BLOCK_HEADER;
+
+			fallthrough;
+
+		case SEQ_BLOCK_HEADER:
+			if (!fill_temp(s, b))
+				return XZ_OK;
+
+			ret = dec_block_header(s);
+			if (ret != XZ_OK)
+				return ret;
+
+			s->sequence = SEQ_BLOCK_UNCOMPRESS;
+
+			fallthrough;
+
+		case SEQ_BLOCK_UNCOMPRESS:
+			ret = dec_block(s, b);
+			if (ret != XZ_STREAM_END)
+				return ret;
+
+			s->sequence = SEQ_BLOCK_PADDING;
+
+			fallthrough;
+
+		case SEQ_BLOCK_PADDING:
+			/*
+			 * Size of Compressed Data + Block Padding
+			 * must be a multiple of four. We don't need
+			 * s->block.compressed for anything else
+			 * anymore, so we use it here to test the size
+			 * of the Block Padding field.
+			 */
+			while (s->block.compressed & 3) {
+				if (b->in_pos == b->in_size)
+					return XZ_OK;
+
+				if (b->in[b->in_pos++] != 0)
+					return XZ_DATA_ERROR;
+
+				++s->block.compressed;
+			}
+
+			s->sequence = SEQ_BLOCK_CHECK;
+
+			fallthrough;
+
+		case SEQ_BLOCK_CHECK:
+			if (s->check_type == XZ_CHECK_CRC32) {
+				ret = crc32_validate(s, b);
+				if (ret != XZ_STREAM_END)
+					return ret;
+			}
+#ifdef XZ_DEC_ANY_CHECK
+			else if (!check_skip(s, b)) {
+				return XZ_OK;
+			}
+#endif
+
+			s->sequence = SEQ_BLOCK_START;
+			break;
+
+		case SEQ_INDEX:
+			ret = dec_index(s, b);
+			if (ret != XZ_STREAM_END)
+				return ret;
+
+			s->sequence = SEQ_INDEX_PADDING;
+
+			fallthrough;
+
+		case SEQ_INDEX_PADDING:
+			while ((s->index.size + (b->in_pos - s->in_start))
+					& 3) {
+				if (b->in_pos == b->in_size) {
+					index_update(s, b);
+					return XZ_OK;
+				}
+
+				if (b->in[b->in_pos++] != 0)
+					return XZ_DATA_ERROR;
+			}
+
+			/* Finish the CRC32 value and Index size. */
+			index_update(s, b);
+
+			/* Compare the hashes to validate the Index field. */
+			if (!memeq(&s->block.hash, &s->index.hash,
+					sizeof(s->block.hash)))
+				return XZ_DATA_ERROR;
+
+			s->sequence = SEQ_INDEX_CRC32;
+
+			fallthrough;
+
+		case SEQ_INDEX_CRC32:
+			ret = crc32_validate(s, b);
+			if (ret != XZ_STREAM_END)
+				return ret;
+
+			s->temp.size = STREAM_HEADER_SIZE;
+			s->sequence = SEQ_STREAM_FOOTER;
+
+			fallthrough;
+
+		case SEQ_STREAM_FOOTER:
+			if (!fill_temp(s, b))
+				return XZ_OK;
+
+			return dec_stream_footer(s);
+		}
+	}
+
+	/* Never reached */
+}
+
+/*
+ * xz_dec_run() is a wrapper for dec_main() to handle some special cases in
+ * multi-call and single-call decoding.
+ *
+ * In multi-call mode, we must return XZ_BUF_ERROR when it seems clear that we
+ * are not going to make any progress anymore. This is to prevent the caller
+ * from calling us infinitely when the input file is truncated or otherwise
+ * corrupt. Since zlib-style API allows that the caller fills the input buffer
+ * only when the decoder doesn't produce any new output, we have to be careful
+ * to avoid returning XZ_BUF_ERROR too easily: XZ_BUF_ERROR is returned only
+ * after the second consecutive call to xz_dec_run() that makes no progress.
+ *
+ * In single-call mode, if we couldn't decode everything and no error
+ * occurred, either the input is truncated or the output buffer is too small.
+ * Since we know that the last input byte never produces any output, we know
+ * that if all the input was consumed and decoding wasn't finished, the file
+ * must be corrupt. Otherwise the output buffer has to be too small or the
+ * file is corrupt in a way that decoding it produces too big output.
+ *
+ * If single-call decoding fails, we reset b->in_pos and b->out_pos back to
+ * their original values. This is because with some filter chains there won't
+ * be any valid uncompressed data in the output buffer unless the decoding
+ * actually succeeds (that's the price to pay of using the output buffer as
+ * the workspace).
+ */
+XZ_EXTERN enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b)
+{
+	size_t in_start;
+	size_t out_start;
+	enum xz_ret ret;
+
+	if (DEC_IS_SINGLE(s->mode))
+		xz_dec_reset(s);
+
+	in_start = b->in_pos;
+	out_start = b->out_pos;
+	ret = dec_main(s, b);
+
+	if (DEC_IS_SINGLE(s->mode)) {
+		if (ret == XZ_OK)
+			ret = b->in_pos == b->in_size
+					? XZ_DATA_ERROR : XZ_BUF_ERROR;
+
+		if (ret != XZ_STREAM_END) {
+			b->in_pos = in_start;
+			b->out_pos = out_start;
+		}
+
+	} else if (ret == XZ_OK && in_start == b->in_pos
+			&& out_start == b->out_pos) {
+		if (s->allow_buf_error)
+			ret = XZ_BUF_ERROR;
+
+		s->allow_buf_error = true;
+	} else {
+		s->allow_buf_error = false;
+	}
+
+	return ret;
+}
+
+XZ_EXTERN struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max)
+{
+	struct xz_dec *s = kmalloc(sizeof(*s), GFP_KERNEL);
+	if (s == NULL)
+		return NULL;
+
+	s->mode = mode;
+
+#ifdef XZ_DEC_BCJ
+	s->bcj = xz_dec_bcj_create(DEC_IS_SINGLE(mode));
+	if (s->bcj == NULL)
+		goto error_bcj;
+#endif
+
+	s->lzma2 = xz_dec_lzma2_create(mode, dict_max);
+	if (s->lzma2 == NULL)
+		goto error_lzma2;
+
+	xz_dec_reset(s);
+	return s;
+
+error_lzma2:
+#ifdef XZ_DEC_BCJ
+	xz_dec_bcj_end(s->bcj);
+error_bcj:
+#endif
+	kfree(s);
+	return NULL;
+}
+
+XZ_EXTERN void xz_dec_reset(struct xz_dec *s)
+{
+	s->sequence = SEQ_STREAM_HEADER;
+	s->allow_buf_error = false;
+	s->pos = 0;
+	s->crc32 = 0;
+	memzero(&s->block, sizeof(s->block));
+	memzero(&s->index, sizeof(s->index));
+	s->temp.pos = 0;
+	s->temp.size = STREAM_HEADER_SIZE;
+}
+
+XZ_EXTERN void xz_dec_end(struct xz_dec *s)
+{
+	if (s != NULL) {
+		xz_dec_lzma2_end(s->lzma2);
+#ifdef XZ_DEC_BCJ
+		xz_dec_bcj_end(s->bcj);
+#endif
+		kfree(s);
+	}
+}