4.18-stable review patch. If anyone has any objections, please let me know.
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From: xiao jin jin.xiao@intel.com
commit 54648cf1ec2d7f4b6a71767799c45676a138ca24 upstream.
We find the memory use-after-free issue in __blk_drain_queue() on the kernel 4.14. After read the latest kernel 4.18-rc6 we think it has the same problem.
Memory is allocated for q->fq in the blk_init_allocated_queue(). If the elevator init function called with error return, it will run into the fail case to free the q->fq.
Then the __blk_drain_queue() uses the same memory after the free of the q->fq, it will lead to the unpredictable event.
The patch is to set q->fq as NULL in the fail case of blk_init_allocated_queue().
Fixes: commit 7c94e1c157a2 ("block: introduce blk_flush_queue to drive flush machinery") Cc: stable@vger.kernel.org Reviewed-by: Ming Lei ming.lei@redhat.com Reviewed-by: Bart Van Assche bart.vanassche@wdc.com Signed-off-by: xiao jin jin.xiao@intel.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- block/blk-core.c | 1 + 1 file changed, 1 insertion(+)
--- a/block/blk-core.c +++ b/block/blk-core.c @@ -1180,6 +1180,7 @@ out_exit_flush_rq: q->exit_rq_fn(q, q->fq->flush_rq); out_free_flush_queue: blk_free_flush_queue(q->fq); + q->fq = NULL; return -ENOMEM; } EXPORT_SYMBOL(blk_init_allocated_queue);