From: Filipe Manana <fdmanana@xxxxxxxx>
[ Upstream commit HEAD ]
commit ccccf3d67294714af2d72a6fd6fd7d73b01c9329 upstream.
If we attempt to clone a 0 length region into a file we can end up
inserting a range in the inode's extent_io tree with a start offset
that is greater then the end offset, which triggers immediately the
following warning:
[ 3914.619057] WARNING: CPU: 17 PID: 4199 at fs/btrfs/extent_io.c:435 insert_state+0x4b/0x10b [btrfs]()
[ 3914.620886] BTRFS: end < start 4095 4096
(...)
[ 3914.638093] Call Trace:
[ 3914.638636] [<ffffffff81425fd9>] dump_stack+0x4c/0x65
[ 3914.639620] [<ffffffff81045390>] warn_slowpath_common+0xa1/0xbb
[ 3914.640789] [<ffffffffa03ca44f>] ? insert_state+0x4b/0x10b [btrfs]
[ 3914.642041] [<ffffffff810453f0>] warn_slowpath_fmt+0x46/0x48
[ 3914.643236] [<ffffffffa03ca44f>] insert_state+0x4b/0x10b [btrfs]
[ 3914.644441] [<ffffffffa03ca729>] __set_extent_bit+0x107/0x3f4 [btrfs]
[ 3914.645711] [<ffffffffa03cb256>] lock_extent_bits+0x65/0x1bf [btrfs]
[ 3914.646914] [<ffffffff8142b2fb>] ? _raw_spin_unlock+0x28/0x33
[ 3914.648058] [<ffffffffa03cbac4>] ? test_range_bit+0xcc/0xde [btrfs]
[ 3914.650105] [<ffffffffa03cb3c3>] lock_extent+0x13/0x15 [btrfs]
[ 3914.651361] [<ffffffffa03db39e>] lock_extent_range+0x3d/0xcd [btrfs]
[ 3914.652761] [<ffffffffa03de1fe>] btrfs_ioctl_clone+0x278/0x388 [btrfs]
[ 3914.654128] [<ffffffff811226dd>] ? might_fault+0x58/0xb5
[ 3914.655320] [<ffffffffa03e0909>] btrfs_ioctl+0xb51/0x2195 [btrfs]
(...)
[ 3914.669271] ---[ end trace 14843d3e2e622fc1 ]---
This later makes the inode eviction handler enter an infinite loop that
keeps dumping the following warning over and over:
[ 3915.117629] WARNING: CPU: 22 PID: 4228 at fs/btrfs/extent_io.c:435 insert_state+0x4b/0x10b [btrfs]()
[ 3915.119913] BTRFS: end < start 4095 4096
(...)
[ 3915.137394] Call Trace:
[ 3915.137913] [<ffffffff81425fd9>] dump_stack+0x4c/0x65
[ 3915.139154] [<ffffffff81045390>] warn_slowpath_common+0xa1/0xbb
[ 3915.140316] [<ffffffffa03ca44f>] ? insert_state+0x4b/0x10b [btrfs]
[ 3915.141505] [<ffffffff810453f0>] warn_slowpath_fmt+0x46/0x48
[ 3915.142709] [<ffffffffa03ca44f>] insert_state+0x4b/0x10b [btrfs]
[ 3915.143849] [<ffffffffa03ca729>] __set_extent_bit+0x107/0x3f4 [btrfs]
[ 3915.145120] [<ffffffffa038c1e3>] ? btrfs_kill_super+0x17/0x23 [btrfs]
[ 3915.146352] [<ffffffff811548f6>] ? deactivate_locked_super+0x3b/0x50
[ 3915.147565] [<ffffffffa03cb256>] lock_extent_bits+0x65/0x1bf [btrfs]
[ 3915.148785] [<ffffffff8142b7e2>] ? _raw_write_unlock+0x28/0x33
[ 3915.149931] [<ffffffffa03bc325>] btrfs_evict_inode+0x196/0x482 [btrfs]
[ 3915.151154] [<ffffffff81168904>] evict+0xa0/0x148
[ 3915.152094] [<ffffffff811689e5>] dispose_list+0x39/0x43
[ 3915.153081] [<ffffffff81169564>] evict_inodes+0xdc/0xeb
[ 3915.154062] [<ffffffff81154418>] generic_shutdown_super+0x49/0xef
[ 3915.155193] [<ffffffff811546d1>] kill_anon_super+0x13/0x1e
[ 3915.156274] [<ffffffffa038c1e3>] btrfs_kill_super+0x17/0x23 [btrfs]
(...)
[ 3915.167404] ---[ end trace 14843d3e2e622fc2 ]---
So just bail out of the clone ioctl if the length of the region to clone
is zero, without locking any extent range, in order to prevent this issue
(same behaviour as a pwrite with a 0 length for example).
This is trivial to reproduce. For example, the steps for the test I just
made for fstests:
mkfs.btrfs -f SCRATCH_DEV
mount SCRATCH_DEV $SCRATCH_MNT
touch $SCRATCH_MNT/foo
touch $SCRATCH_MNT/bar
$CLONER_PROG -s 0 -d 4096 -l 0 $SCRATCH_MNT/foo $SCRATCH_MNT/bar
umount $SCRATCH_MNT
A test case for fstests follows soon.
Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
Reviewed-by: Omar Sandoval <osandov@xxxxxxxxxxx>
Signed-off-by: Chris Mason <clm@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
(cherry picked from commit 449b46275ce58e1d3fc20d1efacd0d0369c6070f)
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
fs/btrfs/ioctl.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 4399f0c..96ea36f 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3654,6 +3654,11 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
if (off + len == src->i_size)
len = ALIGN(src->i_size, bs) - off;
+ if (len == 0) {
+ ret = 0;
+ goto out_unlock;
+ }
+
/* verify the end result is block aligned */
if (!IS_ALIGNED(off, bs) || !IS_ALIGNED(off + len, bs) ||
!IS_ALIGNED(destoff, bs))
--
2.1.0
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