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    Subject[PATCH 4.14 095/140] bcache: fix crashes in duplicate cache device register
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Tang Junhui <tang.junhui@zte.com.cn>

    commit cc40daf91bdddbba72a4a8cd0860640e06668309 upstream.

    Kernel crashed when register a duplicate cache device, the call trace is
    bellow:
    [ 417.643790] CPU: 1 PID: 16886 Comm: bcache-register Tainted: G
    W OE 4.15.5-amd64-preempt-sysrq-20171018 #2
    [ 417.643861] Hardware name: LENOVO 20ERCTO1WW/20ERCTO1WW, BIOS
    N1DET41W (1.15 ) 12/31/2015
    [ 417.643870] RIP: 0010:bdevname+0x13/0x1e
    [ 417.643876] RSP: 0018:ffffa3aa9138fd38 EFLAGS: 00010282
    [ 417.643884] RAX: 0000000000000000 RBX: ffff8c8f2f2f8000 RCX: ffffd6701f8
    c7edf
    [ 417.643890] RDX: ffffa3aa9138fd88 RSI: ffffa3aa9138fd88 RDI: 00000000000
    00000
    [ 417.643895] RBP: ffffa3aa9138fde0 R08: ffffa3aa9138fae8 R09: 00000000000
    1850e
    [ 417.643901] R10: ffff8c8eed34b271 R11: ffff8c8eed34b250 R12: 00000000000
    00000
    [ 417.643906] R13: ffffd6701f78f940 R14: ffff8c8f38f80000 R15: ffff8c8ea7d
    90000
    [ 417.643913] FS: 00007fde7e66f500(0000) GS:ffff8c8f61440000(0000) knlGS:
    0000000000000000
    [ 417.643919] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    [ 417.643925] CR2: 0000000000000314 CR3: 00000007e6fa0001 CR4: 00000000003
    606e0
    [ 417.643931] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 00000000000
    00000
    [ 417.643938] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 00000000000
    00400
    [ 417.643946] Call Trace:
    [ 417.643978] register_bcache+0x1117/0x1270 [bcache]
    [ 417.643994] ? slab_pre_alloc_hook+0x15/0x3c
    [ 417.644001] ? slab_post_alloc_hook.isra.44+0xa/0x1a
    [ 417.644013] ? kernfs_fop_write+0xf6/0x138
    [ 417.644020] kernfs_fop_write+0xf6/0x138
    [ 417.644031] __vfs_write+0x31/0xcc
    [ 417.644043] ? current_kernel_time64+0x10/0x36
    [ 417.644115] ? __audit_syscall_entry+0xbf/0xe3
    [ 417.644124] vfs_write+0xa5/0xe2
    [ 417.644133] SyS_write+0x5c/0x9f
    [ 417.644144] do_syscall_64+0x72/0x81
    [ 417.644161] entry_SYSCALL_64_after_hwframe+0x3d/0xa2
    [ 417.644169] RIP: 0033:0x7fde7e1c1974
    [ 417.644175] RSP: 002b:00007fff13009a38 EFLAGS: 00000246 ORIG_RAX: 0000000
    000000001
    [ 417.644183] RAX: ffffffffffffffda RBX: 0000000001658280 RCX: 00007fde7e1c
    1974
    [ 417.644188] RDX: 000000000000000a RSI: 0000000001658280 RDI: 000000000000
    0001
    [ 417.644193] RBP: 000000000000000a R08: 0000000000000003 R09: 000000000000
    0077
    [ 417.644198] R10: 000000000000089e R11: 0000000000000246 R12: 000000000000
    0001
    [ 417.644203] R13: 000000000000000a R14: 7fffffffffffffff R15: 000000000000
    0000
    [ 417.644213] Code: c7 c2 83 6f ee 98 be 20 00 00 00 48 89 df e8 6c 27 3b 0
    0 48 89 d8 5b c3 0f 1f 44 00 00 48 8b 47 70 48 89 f2 48 8b bf 80 00 00 00 <8
    b> b0 14 03 00 00 e9 73 ff ff ff 0f 1f 44 00 00 48 8b 47 40 39
    [ 417.644302] RIP: bdevname+0x13/0x1e RSP: ffffa3aa9138fd38
    [ 417.644306] CR2: 0000000000000314

    When registering duplicate cache device in register_cache(), after failure
    on calling register_cache_set(), bch_cache_release() will be called, then
    bdev will be freed, so bdevname(bdev, name) caused kernel crash.

    Since bch_cache_release() will free bdev, so in this patch we make sure
    bdev being freed if register_cache() fail, and do not free bdev again in
    register_bcache() when register_cache() fail.

    Signed-off-by: Tang Junhui <tang.junhui@zte.com.cn>
    Reported-by: Marc MERLIN <marc@merlins.org>
    Tested-by: Michael Lyle <mlyle@lyle.org>
    Reviewed-by: Michael Lyle <mlyle@lyle.org>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: Jens Axboe <axboe@kernel.dk>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/md/bcache/super.c | 16 ++++++++++------
    1 file changed, 10 insertions(+), 6 deletions(-)

    --- a/drivers/md/bcache/super.c
    +++ b/drivers/md/bcache/super.c
    @@ -1181,7 +1181,7 @@ static void register_bdev(struct cache_s

    return;
    err:
    - pr_notice("error opening %s: %s", bdevname(bdev, name), err);
    + pr_notice("error %s: %s", bdevname(bdev, name), err);
    bcache_device_stop(&dc->disk);
    }

    @@ -1849,6 +1849,8 @@ static int register_cache(struct cache_s
    const char *err = NULL; /* must be set for any error case */
    int ret = 0;

    + bdevname(bdev, name);
    +
    memcpy(&ca->sb, sb, sizeof(struct cache_sb));
    ca->bdev = bdev;
    ca->bdev->bd_holder = ca;
    @@ -1857,11 +1859,12 @@ static int register_cache(struct cache_s
    ca->sb_bio.bi_io_vec[0].bv_page = sb_page;
    get_page(sb_page);

    - if (blk_queue_discard(bdev_get_queue(ca->bdev)))
    + if (blk_queue_discard(bdev_get_queue(bdev)))
    ca->discard = CACHE_DISCARD(&ca->sb);

    ret = cache_alloc(ca);
    if (ret != 0) {
    + blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
    if (ret == -ENOMEM)
    err = "cache_alloc(): -ENOMEM";
    else
    @@ -1884,14 +1887,14 @@ static int register_cache(struct cache_s
    goto out;
    }

    - pr_info("registered cache device %s", bdevname(bdev, name));
    + pr_info("registered cache device %s", name);

    out:
    kobject_put(&ca->kobj);

    err:
    if (err)
    - pr_notice("error opening %s: %s", bdevname(bdev, name), err);
    + pr_notice("error %s: %s", name, err);

    return ret;
    }
    @@ -1980,6 +1983,7 @@ static ssize_t register_bcache(struct ko
    if (err)
    goto err_close;

    + err = "failed to register device";
    if (SB_IS_BDEV(sb)) {
    struct cached_dev *dc = kzalloc(sizeof(*dc), GFP_KERNEL);
    if (!dc)
    @@ -1994,7 +1998,7 @@ static ssize_t register_bcache(struct ko
    goto err_close;

    if (register_cache(sb, sb_page, bdev, ca) != 0)
    - goto err_close;
    + goto err;
    }
    out:
    if (sb_page)
    @@ -2007,7 +2011,7 @@ out:
    err_close:
    blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
    err:
    - pr_info("error opening %s: %s", path, err);
    + pr_info("error %s: %s", path, err);
    ret = -EINVAL;
    goto out;
    }

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