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Subject[PATCH] block: fix memleak when __blk_rq_map_user_iov() is failed
Date
When I doing fuzzy test, get the memleak report:

BUG: memory leak
unreferenced object 0xffff88837af80000 (size 4096):
comm "memleak", pid 3557, jiffies 4294817681 (age 112.499s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
20 00 00 00 10 01 00 00 00 00 00 00 01 00 00 00 ...............
backtrace:
[<000000001c894df8>] bio_alloc_bioset+0x393/0x590
[<000000008b139a3c>] bio_copy_user_iov+0x300/0xcd0
[<00000000a998bd8c>] blk_rq_map_user_iov+0x2f1/0x5f0
[<000000005ceb7f05>] blk_rq_map_user+0xf2/0x160
[<000000006454da92>] sg_common_write.isra.21+0x1094/0x1870
[<00000000064bb208>] sg_write.part.25+0x5d9/0x950
[<000000004fc670f6>] sg_write+0x5f/0x8c
[<00000000b0d05c7b>] __vfs_write+0x7c/0x100
[<000000008e177714>] vfs_write+0x1c3/0x500
[<0000000087d23f34>] ksys_write+0xf9/0x200
[<000000002c8dbc9d>] do_syscall_64+0x9f/0x4f0
[<00000000678d8e9a>] entry_SYSCALL_64_after_hwframe+0x49/0xbe

If __blk_rq_map_user_iov() is failed in blk_rq_map_user_iov(),
the bio(s) which is allocated before this failing will leak. The
refcount of the bio(s) is init to 1 and increased to 2 by calling
bio_get(), but __blk_rq_unmap_user() only decrease it to 1, so
the bio cannot be freed. Fix it by calling blk_rq_unmap_user().

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
block/blk-map.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-map.c b/block/blk-map.c
index 3a62e471d81b..b0790268ed9d 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -151,7 +151,7 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
return 0;

unmap_rq:
- __blk_rq_unmap_user(bio);
+ blk_rq_unmap_user(bio);
fail:
rq->bio = NULL;
return ret;
--
2.17.1
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