perf symbols: Bounds-check descsz in sysfs__read_build_id() GNU fallback

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When sysfs__read_build_id() matches NT_GNU_BUILD_ID with the right
namesz but the name content is not "GNU", it falls back to reading
descsz bytes into the stack buffer bf[BUFSIZ]:

    } else if (read(fd, bf, descsz) != (ssize_t)descsz)

Unlike the else branch which validates namesz + descsz against
sizeof(bf), this path passes descsz directly to read() without any
bounds check.  A crafted sysfs file with a large n_descsz overflows
the 8192-byte stack buffer.

Add a descsz > sizeof(bf) check before the read, breaking out of
the loop on oversized values.

Fixes: e5a1845fc0 ("perf symbols: Split out util/symbol-elf.c")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Assisted-by: Claude:claude-opus-4.6
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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Arnaldo Carvalho de Melo 2026-06-07 22:40:20 -03:00

parent e1a2c9d70b

commit 1b4e9fbdea

1 changed files with 7 additions and 2 deletions

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tools/perf/util/symbol-elf.c

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