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 [groeck: backport to v4.4.y/v4.9.y (context change)] Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Alessio Balsini balsini@android.com 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 @@ -881,6 +881,7 @@ blk_init_allocated_queue(struct request_
fail: blk_free_flush_queue(q->fq); + q->fq = NULL; return NULL; } EXPORT_SYMBOL(blk_init_allocated_queue);