Looks good. Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@xxxxxxx> On 02/06/2020 06:28 AM, Jan Kara wrote: > KASAN is reporting that __blk_add_trace() has a use-after-free issue > when accessing q->blk_trace. Indeed the switching of block tracing (and > thus eventual freeing of q->blk_trace) is completely unsynchronized with > the currently running tracing and thus it can happen that the blk_trace > structure is being freed just while __blk_add_trace() works on it. > Protect accesses to q->blk_trace by RCU during tracing and make sure we > wait for the end of RCU grace period when shutting down tracing. Luckily > that is rare enough event that we can afford that. Note that postponing > the freeing of blk_trace to an RCU callback should better be avoided as > it could have unexpected user visible side-effects as debugfs files > would be still existing for a short while block tracing has been shut > down. > > Link:https://bugzilla.kernel.org/show_bug.cgi?id=205711 > CC:stable@xxxxxxxxxxxxxxx > Reported-by: Tristan<tristmd@xxxxxxxxx> > Signed-off-by: Jan Kara<jack@xxxxxxx>
