From 959a35f13eb785f982d79b1aaa75872d05c821da Mon Sep 17 00:00:00 2001
From: Jeff Moyer <jmoyer@redhat.com>
Date: Tue, 3 Dec 2013 14:23:00 -0700
Subject: [PATCH] blk-mq: fix dereference of rq->mq_ctx if allocation fails
If __GFP_WAIT isn't set and we fail allocating, when we go
to drop the reference on the ctx, we will attempt to dereference
the NULL rq. Fix that.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
block/blk-mq.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index cdc629cf075b..70fd6f996600 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -202,10 +202,12 @@ static struct request *blk_mq_alloc_request_pinned(struct request_queue *q,
if (rq) {
blk_mq_rq_ctx_init(q, ctx, rq, rw);
break;
- } else if (!(gfp & __GFP_WAIT))
- break;
+ }
blk_mq_put_ctx(ctx);
+ if (!(gfp & __GFP_WAIT))
+ break;
+
__blk_mq_run_hw_queue(hctx);
blk_mq_wait_for_tags(hctx->tags);
} while (1);
@@ -222,7 +224,8 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
return NULL;
rq = blk_mq_alloc_request_pinned(q, rw, gfp, reserved);
- blk_mq_put_ctx(rq->mq_ctx);
+ if (rq)
+ blk_mq_put_ctx(rq->mq_ctx);
return rq;
}
@@ -235,7 +238,8 @@ struct request *blk_mq_alloc_reserved_request(struct request_queue *q, int rw,
return NULL;
rq = blk_mq_alloc_request_pinned(q, rw, gfp, true);
- blk_mq_put_ctx(rq->mq_ctx);
+ if (rq)
+ blk_mq_put_ctx(rq->mq_ctx);
return rq;
}
EXPORT_SYMBOL(blk_mq_alloc_reserved_request);
--
GitLab