lib/buildid: harden build ID parsing logic

Harden build ID parsing logic, adding explicit READ_ONCE() where it's
important to have a consistent value read and validated just once.

Also, as pointed out by Andi Kleen, we need to make sure that entire ELF
note is within a page bounds, so move the overflow check up and add an
extra note_size boundaries validation.

Fixes tag below points to the code that moved this code into
lib/buildid.c, and then subsequently was used in perf subsystem, making
this code exposed to perf_event_open() users in v5.12+.

Cc: [email protected]
Reviewed-by: Eduard Zingerman <[email protected]>
Reviewed-by: Jann Horn <[email protected]>
Suggested-by: Andi Kleen <[email protected]>
Fixes: bd7525dacd7e ("bpf: Move stack_map_get_build_id into lib")
Signed-off-by: Andrii Nakryiko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>

0 files changed, 0 insertions, 0 deletions