From: Douglas Gilbert <dgilbert@interlog.com>
Date: Sun, 14 Jan 2018 22:00:48 +0000 (-0500)
Subject: blk_rq_map_user_iov: fix error override
X-Git-Tag: v4.16-rc1~184^2~30
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=69e0927b3774563c19b5fb32e91d75edc147fb62;p=linux.git

blk_rq_map_user_iov: fix error override

During stress tests by syzkaller on the sg driver the block layer
infrequently returns EINVAL. Closer inspection shows the block
layer was trying to return ENOMEM (which is much more
understandable) but for some reason overroad that useful error.

Patch below does not show this (unchanged) line:
   ret =__blk_rq_map_user_iov(rq, map_data, &i, gfp_mask, copy);
That 'ret' was being overridden when that function failed.

Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/block/blk-map.c b/block/blk-map.c
index b21f8e86f120..209eb3b45c54 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -114,7 +114,7 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
 	unsigned long align = q->dma_pad_mask | queue_dma_alignment(q);
 	struct bio *bio = NULL;
 	struct iov_iter i;
-	int ret;
+	int ret = -EINVAL;
 
 	if (!iter_is_iovec(iter))
 		goto fail;
@@ -143,7 +143,7 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
 	__blk_rq_unmap_user(bio);
 fail:
 	rq->bio = NULL;
-	return -EINVAL;
+	return ret;
 }
 EXPORT_SYMBOL(blk_rq_map_user_iov);