[v2] btrfs: fix null pointer deref when target device is missing
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Message ID 20180224114356.18029-1-anand.jain@oracle.com
State New
Headers show

Commit Message

Anand Jain Feb. 24, 2018, 11:43 a.m. UTC
The replace target device can be missing when mounted with -o degraded,
but we wont allocate a missing btrfs_device to it. So check the device
before access.

BUG: unable to handle kernel NULL pointer dereference at 00000000000000b0
IP: btrfs_destroy_dev_replace_tgtdev+0x43/0xf0 [btrfs]
Call Trace:
btrfs_dev_replace_cancel+0x15f/0x180 [btrfs]
btrfs_ioctl+0x2216/0x2590 [btrfs]

Signed-off-by: Anand Jain <anand.jain@oracle.com>
v1->v2: Fix change log. Fix $subject.
  Old $subject
    btrfs: fix NPD when target device is missing

 fs/btrfs/dev-replace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index c97969b2abbd..e279f04b3388 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -312,7 +312,7 @@  void btrfs_after_dev_replace_commit(struct btrfs_fs_info *fs_info)
 static char* btrfs_dev_name(struct btrfs_device *device)
-	if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state))
+	if (!device || test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state))
 		return "<missing disk>";
 		return rcu_str_deref(device->name);