blk_rq_map_user_iov: fix error override

BugLink: http://bugs.launchpad.net/bugs/1752119
commit 69e0927b3774563c19b5fb32e91d75edc147fb62 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

diff --git a/block/blk-map.c b/block/blk-map.c
index d3a94719f03fb2af81d6270d6fc9ed58f0dde373..db9373bd31aca0e9393dd77ec9ef5f404d88923e 100644 (file)
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -119,7 +119,7 @@ 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;
@@ -148,7 +148,7 @@ unmap_rq:
        __blk_rq_unmap_user(bio);
 fail:
        rq->bio = NULL;
-       return -EINVAL;
+       return ret;
 }
 EXPORT_SYMBOL(blk_rq_map_user_iov);