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1b4e9fbdea
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>