path: root/kernel/bpf/arraymap.c
diff options
authorAlexei Starovoitov <>2015-05-28 19:26:02 -0700
committerDavid S. Miller <>2015-05-31 00:27:51 -0700
commitabf2e7d6e2e315b32ee00067a69aaad2cf4e1b3f (patch)
tree073ee9134421f2ab9edcd226a48de1a4bea72554 /kernel/bpf/arraymap.c
parentd1f5f2bb91094c9e6f7c98610d637ffdaedef116 (diff)
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 <> Signed-off-by: Alexei Starovoitov <> Acked-by: Daniel Borkmann <> Signed-off-by: David S. Miller <>
Diffstat (limited to 'kernel/bpf/arraymap.c')
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;