kallsyms: Disable preemption for find_kallsyms_symbol_value
authorJiri Olsa <jolsa@kernel.org>
Mon, 3 Apr 2023 22:02:54 +0000 (00:02 +0200)
committerAndrii Nakryiko <andrii@kernel.org>
Wed, 5 Apr 2023 00:11:59 +0000 (17:11 -0700)
commitd099f594ad5650e8d8232b5f31f5f90104e65def
treee127edade69cd05d27e5c026aff374125de683f8
parente8f59d84f43deab59bb86ff9e12cd4d542a4bb34
kallsyms: Disable preemption for find_kallsyms_symbol_value

Artem reported suspicious RCU usage [1]. The reason is that verifier
calls find_kallsyms_symbol_value with preemption enabled which will
trigger suspicious RCU usage warning in rcu_dereference_sched call.

Disabling preemption in find_kallsyms_symbol_value and adding
__find_kallsyms_symbol_value function.

Fixes: 31bf1dbccfb0 ("bpf: Fix attaching fentry/fexit/fmod_ret/lsm to modules")
Reported-by: Artem Savkov <asavkov@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Artem Savkov <asavkov@redhat.com>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/bpf/20230403220254.2191240-1-jolsa@kernel.org
[1] https://lore.kernel.org/bpf/ZBrPMkv8YVRiWwCR@samus.usersys.redhat.com/
kernel/module/kallsyms.c