diff options
| author | Jakub Sitnicki <jakub@cloudflare.com> | 2019-08-21 14:17:20 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-09-21 07:18:34 +0200 |
| commit | 5e0251d82954b488c652befe3f330bacfe0fadce (patch) | |
| tree | 346bb7c6d170ad79dd7918e182bdbc97a29d13b2 /net | |
| parent | 31320b857d1365cceaa663b078a3713e183ecad4 (diff) | |
flow_dissector: Fix potential use-after-free on BPF_PROG_DETACH
[ Upstream commit db38de39684dda2bf307f41797db2831deba64e9 ]
Call to bpf_prog_put(), with help of call_rcu(), queues an RCU-callback to
free the program once a grace period has elapsed. The callback can run
together with new RCU readers that started after the last grace period.
New RCU readers can potentially see the "old" to-be-freed or already-freed
pointer to the program object before the RCU update-side NULLs it.
Reorder the operations so that the RCU update-side resets the protected
pointer before the end of the grace period after which the program will be
freed.
Fixes: d58e468b1112 ("flow_dissector: implements flow dissector BPF hook")
Reported-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Acked-by: Petar Penkov <ppenkov@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/flow_dissector.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index edd622956083..b15c0c0f6e55 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -138,8 +138,8 @@ int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr) mutex_unlock(&flow_dissector_mutex); return -ENOENT; } - bpf_prog_put(attached); RCU_INIT_POINTER(net->flow_dissector_prog, NULL); + bpf_prog_put(attached); mutex_unlock(&flow_dissector_mutex); return 0; } |