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    Subject[PATCH 5.4 128/165] block: fix memleak when __blk_rq_map_user_iov() is failed
    Date
    From: Yang Yingliang <yangyingliang@huawei.com>

    [ Upstream commit 3b7995a98ad76da5597b488fa84aa5a56d43b608 ]

    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().

    Reviewed-by: Bob Liu <bob.liu@oracle.com>
    Reported-by: Hulk Robot <hulkci@huawei.com>
    Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
    Signed-off-by: Jens Axboe <axboe@kernel.dk>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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;
    --
    2.20.1


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