From c19199167c87841006350cc7c0a59881416e8748 Mon Sep 17 00:00:00 2001 From: xiao jin Date: Mon, 30 Jul 2018 14:11:12 +0800 Subject: block: blk_init_allocated_queue() set q->fq as NULL in the fail case 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: Reviewed-by: Ming Lei Reviewed-by: Bart Van Assche Signed-off-by: xiao jin Signed-off-by: Jens Axboe [groeck: backport to v4.4.y/v4.9.y (context change)] Signed-off-by: Guenter Roeck Signed-off-by: Alessio Balsini Signed-off-by: Greg Kroah-Hartman --- block/blk-core.c | 1 + 1 file changed, 1 insertion(+) (limited to 'block') diff --git a/block/blk-core.c b/block/blk-core.c index 77b99bf16c83..bdb906bbfe19 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -881,6 +881,7 @@ blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn, fail: blk_free_flush_queue(q->fq); + q->fq = NULL; return NULL; } EXPORT_SYMBOL(blk_init_allocated_queue); -- cgit v1.2.3