Re: [PATCH 01/12] perf jitdump: Fix extended header read that always fails

[sashiko-bot@kernel.org]

> From: Arnaldo Carvalho de Melo <acme@redhat.com>
> 
> jit_open() sets bsz = bs before the fread() that uses bs - bsz as the
> read size, making the expression always evaluate to zero.  fread() with
> size 0 returns 0, which triggers the ret != 1 error path — so extended
> jitdump headers (total_size > sizeof(header)) have been silently broken
> since the original implementation.
> 
> Additionally, when 0 < bs <= bsz the if (bs > bsz) block is skipped
> entirely, leaving extended header bytes unread in the stream.  Subsequent
> jit_get_next_entry() calls then parse those leftover bytes as a
> jr_prefix, corrupting the record stream.
> 
> Fix by separating the buffer growth from the read: realloc only when
> bs > bsz, then unconditionally fread bs bytes when bs > 0.
> 
> Fixes: 9b07e27f88b9cd78 ("perf inject: Add jitdump mmap injection support")
> Reported-by: sashiko-bot <sashiko-bot@kernel.org>
> Reviewed-by: Ian Rogers <irogers@google.com>
> Cc: Stephane Eranian <eranian@google.com>
> Cc: Ian Rogers <irogers@google.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Assisted-by: LLM
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260831131110.4681-1-acme@kernel.org?part=1