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| author | Jan Kara <jack@suse.cz> | 2020-02-06 15:28:12 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-02-25 08:40:07 -0700 |
| commit | c780e86dd48ef6467a1146cf7d0fe1e05a635039 (patch) | |
| tree | adc26e0463d952242d1a18b9de9b2226eff81e17 /include/linux/blkdev.h | |
| parent | 01e99aeca3979600302913cef3f89076786f32c8 (diff) | |
| download | lwn-c780e86dd48ef6467a1146cf7d0fe1e05a635039.tar.gz lwn-c780e86dd48ef6467a1146cf7d0fe1e05a635039.zip | |
blktrace: Protect q->blk_trace with RCU
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@vger.kernel.org
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reported-by: Tristan Madani <tristmd@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include/linux/blkdev.h')
| -rw-r--r-- | include/linux/blkdev.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 053ea4b51988..10455b2bbbb4 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -524,7 +524,7 @@ struct request_queue { unsigned int sg_reserved_size; int node; #ifdef CONFIG_BLK_DEV_IO_TRACE - struct blk_trace *blk_trace; + struct blk_trace __rcu *blk_trace; struct mutex blk_trace_mutex; #endif /* |