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Deepanshu Kartikey 02d209bb01 tracing/dma: Cap dma_map_sg tracepoint arrays to prevent buffer overflow 
[ Upstream commit daafcc0ef0 ]

The dma_map_sg tracepoint can trigger a perf buffer overflow when
tracing large scatter-gather lists. With devices like virtio-gpu
creating large DRM buffers, nents can exceed 1000 entries, resulting
in:

  phys_addrs: 1000 * 8 bytes = 8,000 bytes
  dma_addrs:  1000 * 8 bytes = 8,000 bytes
  lengths:    1000 * 4 bytes = 4,000 bytes
  Total: ~20,000 bytes

This exceeds PERF_MAX_TRACE_SIZE (8192 bytes), causing:

  WARNING: CPU: 0 PID: 5497 at kernel/trace/trace_event_perf.c:405
  perf buffer not large enough, wanted 24620, have 8192

Cap all three dynamic arrays at 128 entries using min() in the array
size calculation. This ensures arrays are only as large as needed
(up to the cap), avoiding unnecessary memory allocation for small
operations while preventing overflow for large ones.

The tracepoint now records the full nents/ents counts and a truncated
flag so users can see when data has been capped.

Changes in v2:
- Use min(nents, DMA_TRACE_MAX_ENTRIES) for dynamic array sizing
  instead of fixed DMA_TRACE_MAX_ENTRIES allocation (feedback from
  Steven Rostedt)
- This allocates only what's needed up to the cap, avoiding waste
  for small operations

Reported-by: syzbot+28cea38c382fd15e751a@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=28cea38c382fd15e751a
Tested-by: syzbot+28cea38c382fd15e751a@syzkaller.appspotmail.com
Signed-off-by: Deepanshu Kartikey <Kartikey406@gmail.com>
Reviwed-by: Sean Anderson <sean.anderson@linux.dev>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260130155215.69737-1-kartikey406@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2026-02-19 16:29:54 +01:00
arch riscv: Sanitize syscall table indexing under speculation 2026-02-11 13:40:20 +01:00
block block,bfq: fix aux stat accumulation destination 2026-02-11 13:40:19 +01:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: authencesn - reject too-short AAD (assoclen<8) to match ESP/ESN spec 2026-01-30 10:28:39 +01:00
Documentation gpiolib-acpi: Update file references in the Documentation and MAINTAINERS 2026-02-11 13:40:29 +01:00
drivers platform/x86: panasonic-laptop: Fix sysfs group leak in error path 2026-02-19 16:29:53 +01:00
fs romfs: check sb_set_blocksize() return value 2026-02-19 16:29:52 +01:00
include tracing/dma: Cap dma_map_sg tracepoint arrays to prevent buffer overflow 2026-02-19 16:29:54 +01:00
init init: handle bootloader identifier in kernel parameters 2025-10-19 16:33:50 +02:00
io_uring io_uring/rw: recycle buffers manually for non-mshot reads 2026-02-12 13:14:56 +01:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:11:22 +01:00
kernel ring-buffer: Avoid softlockup in ring_buffer_resize() during memory free 2026-02-11 13:40:21 +01:00
lib procfs: avoid fetching build ID while holding VMA lock 2026-02-11 13:40:18 +01:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm, shmem: prevent infinite loop on truncate race 2026-02-11 13:40:17 +01:00
net mptcp: fix race in mptcp_pm_nl_flush_addrs_doit() 2026-02-16 10:18:45 +01:00
rust rust: rbtree: fix documentation typo in CursorMut peek_next method 2026-02-06 16:55:44 +01:00
samples samples/ftrace: Adjust LoongArch register restore order in direct calls 2026-01-08 10:14:50 +01:00
scripts scripts: generate_rust_analyzer: Add compiler_builtins -> core dep 2026-02-06 16:55:47 +01:00
security keys/trusted_keys: fix handle passed to tpm_buf_append_name during unseal 2026-01-30 10:28:44 +01:00
sound ASoC: cs42l43: Correct handling of 3-pole jack load detection 2026-02-19 16:29:53 +01:00
tools vsock/test: verify socket options after setting them 2026-02-12 13:14:57 +01:00
usr kbuild: uapi: Strip comments before size type check 2025-11-13 15:34:35 -05:00
virt KVM: Don't clobber irqfd routing type when deassigning irqfd 2026-02-11 13:40:17 +01:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: give Clippy the minimum supported Rust version 2025-08-01 09:48:44 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: introduce .clippy.toml 2025-03-13 13:01:42 +01:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove self from DSA entry 2024-11-03 12:52:38 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS gpiolib-acpi: Update file references in the Documentation and MAINTAINERS 2026-02-11 13:40:29 +01:00
Makefile Linux 6.12.73 2026-02-16 17:09:13 +01:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.