From: xiao jin <[email protected]>
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: <[email protected]>
Reviewed-by: Ming Lei <[email protected]>
Reviewed-by: Bart Van Assche <[email protected]>
Signed-off-by: xiao jin <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
[groeck: backport to v4.4.y/v4.9.y (context change)]
Signed-off-by: Guenter Roeck <[email protected]>
Signed-off-by: Alessio Balsini <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
block/blk-core.c | 1 +
1 file changed, 1 insertion(+)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -870,6 +870,7 @@ blk_init_allocated_queue(struct request_
fail:
blk_free_flush_queue(q->fq);
+ q->fq = NULL;
return NULL;
}
EXPORT_SYMBOL(blk_init_allocated_queue);
