bpf: fix a rcu usage warning in bpf_prog_array_copy_core()

Commit 394e40a29788 ("bpf: extend bpf_prog_array to store pointers
to the cgroup storage") refactored the bpf_prog_array_copy_core()
to accommodate new structure bpf_prog_array_item which contains
bpf_prog array itself.

In the old code, we had
   perf_event_query_prog_array():
     mutex_lock(...)
     bpf_prog_array_copy_call():
       prog = rcu_dereference_check(array, 1)->progs
       bpf_prog_array_copy_core(prog, ...)
     mutex_unlock(...)

With the above commit, we had
   perf_event_query_prog_array():
     mutex_lock(...)
     bpf_prog_array_copy_call():
       bpf_prog_array_copy_core(array, ...):
         item = rcu_dereference(array)->items;
         ...
     mutex_unlock(...)

The new code will trigger a lockdep rcu checking warning.
The fix is to change rcu_dereference() to rcu_dereference_check()
to prevent such a warning.

Reported-by: [email protected]
Fixes: 394e40a29788 ("bpf: extend bpf_prog_array to store pointers to the cgroup storage")
Cc: Roman Gushchin <[email protected]>
Signed-off-by: Yonghong Song <[email protected]>
Acked-by: Alexei Starovoitov <[email protected]>
Acked-by: Roman Gushchin <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>

0 files changed, 0 insertions, 0 deletions