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SubjectRe: [PATCH] block: fix memleak when __blk_rq_map_user_iov() is failed
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On 12/18/19 4:44 PM, Yang Yingliang wrote:
> 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>

Good catch! Looks fine to me.
Reviewed-by: Bob Liu <bob.liu@oracle.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;
>

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