bpf: Check the helper function is valid in get_helper_proto

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[ Upstream commit e4414b01c1 ]

kernel test robot reported verifier bug [1] where the helper func
pointer could be NULL due to disabled config option.

As Alexei suggested we could check on that in get_helper_proto
directly. Marking tail_call helper func with BPF_PTR_POISON,
because it is unused by design.

  [1] https://lore.kernel.org/oe-lkp/202507160818.68358831-lkp@intel.com

Reported-by: kernel test robot <oliver.sang@intel.com>
Reported-by: syzbot+a9ed3d9132939852d0df@syzkaller.appspotmail.com
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Paul Chaignon <paul.chaignon@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20250814200655.945632-1-jolsa@kernel.org
Closes: https://lore.kernel.org/oe-lkp/202507160818.68358831-lkp@intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

...

This commit is contained in:

Jiri Olsa 2025-08-14 22:06:55 +02:00 • committed by Greg Kroah-Hartman

parent ecb6383b79

commit 3d429cb127

2 changed files with 5 additions and 2 deletions

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5

kernel/bpf/core.c

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2

kernel/bpf/verifier.c

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