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| author | Alexei Starovoitov <ast@plumgrid.com> | 2015-05-29 04:26:02 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-05-31 09:27:51 +0200 |
| commit | abf2e7d6e2e315b32ee00067a69aaad2cf4e1b3f (patch) | |
| tree | 073ee9134421f2ab9edcd226a48de1a4bea72554 /kernel/bpf/arraymap.c | |
| parent | Merge branch 'hv_netvsc-next' (diff) | |
| download | linux-abf2e7d6e2e315b32ee00067a69aaad2cf4e1b3f.tar.xz linux-abf2e7d6e2e315b32ee00067a69aaad2cf4e1b3f.zip | |
bpf: add missing rcu protection when releasing programs from prog_array
Normally the program attachment place (like sockets, qdiscs) takes
care of rcu protection and calls bpf_prog_put() after a grace period.
The programs stored inside prog_array may not be attached anywhere,
so prog_array needs to take care of preserving rcu protection.
Otherwise bpf_tail_call() will race with bpf_prog_put().
To solve that introduce bpf_prog_put_rcu() helper function and use
it in 3 places where unattached program can decrement refcnt:
closing program fd, deleting/replacing program in prog_array.
Fixes: 04fd61ab36ec ("bpf: allow bpf programs to tail-call other bpf programs")
Reported-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf/arraymap.c')
| -rw-r--r-- | kernel/bpf/arraymap.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 614bcd4c1d74..cb31229a6fa4 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -202,7 +202,7 @@ static int prog_array_map_update_elem(struct bpf_map *map, void *key, old_prog = xchg(array->prog + index, prog); if (old_prog) - bpf_prog_put(old_prog); + bpf_prog_put_rcu(old_prog); return 0; } @@ -218,7 +218,7 @@ static int prog_array_map_delete_elem(struct bpf_map *map, void *key) old_prog = xchg(array->prog + index, NULL); if (old_prog) { - bpf_prog_put(old_prog); + bpf_prog_put_rcu(old_prog); return 0; } else { return -ENOENT; |