On 8/21/19 2:17 PM, Jakub Sitnicki wrote:
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@xxxxxxxxxxxxxx>
Signed-off-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
Applied, thanks!
