bpf: Remove bpf_lsm_file_mprotect from sleepable list.

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Technically the bpf programs can sleep while attached to bpf_lsm_file_mprotect,
but such programs need to access user memory. So they're in might_fault()
category. Which means they cannot be called from file_mprotect lsm hook that
takes write lock on mm->mmap_lock.
Adjust the test accordingly.

Also add might_fault() to __bpf_prog_enter_sleepable() to catch such deadlocks early.

Fixes: 1e6c62a882 ("bpf: Introduce sleepable BPF programs")
Fixes: e68a144547 ("selftests/bpf: Add sleepable tests")
Reported-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200831201651.82447-1-alexei.starovoitov@gmail.com

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This commit is contained in:

Alexei Starovoitov 2020-08-31 13:16:51 -07:00 • committed by Daniel Borkmann

parent b69e56cf76

commit f56407fa6e

3 changed files with 18 additions and 18 deletions

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1

kernel/bpf/trampoline.c

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1

kernel/bpf/verifier.c

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34

tools/testing/selftests/bpf/progs/lsm.c

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