| Message ID | 20231110114806.3366681-1-lizhi.xu@windriver.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | btrfs: fix warning in create_pending_snapshot | expand |
On 2023/11/10 22:18, Lizhi Xu wrote: > r0 = open(&(0x7f0000000080)='./file0\x00', 0x0, 0x0) > ioctl$BTRFS_IOC_QUOTA_CTL(r0, 0xc0109428, &(0x7f0000000000)={0x1}) > r1 = openat$cgroup_ro(0xffffffffffffff9c, &(0x7f0000000100)='blkio.bfq.time_recursive\x00', 0x275a, 0x0) > ioctl$BTRFS_IOC_QGROUP_CREATE(r1, 0x4010942a, &(0x7f0000000640)={0x1, 0x100}) > r2 = openat(0xffffffffffffff9c, &(0x7f0000000500)='.\x00', 0x0, 0x0) > ioctl$BTRFS_IOC_SNAP_CREATE(r0, 0x50009401, &(0x7f0000000a80)={{r2}, > > From the logs, it can be seen that syz can execute to btrfs_ioctl_qgroup_create() > through two paths. > Syz enters btrfs_ioctl_qgroup_create() by calling ioctl$BTRFS_IOC_QGROUP_CREATE( > r1, 0x4010942a,&(0x7f000000 640)={0x1, 0x100}) or ioctl$BTRFS_IOC_SNAP_CREATE(r0, > 0x50009401,&(0x7f000000 a80)={r2}," respectively; > > The most crucial thing is that when calling ioctl$BTRFS_IOC_QGROUP_CREATE, > the passed parameter qgroupid value is 256, while BTRFS_FIRST_FREE_OBJECTID > is also equal to 256, indicating that the passed parameter qgroupid is > obviously incorrect. This conclusion looks incorrect to me. Subvolumes are allowed to have any id in the range [BTRFS_FIRST_TREE_OBJECTID, BTRFS_LAST_TREE_OBJECTID]. In fact, you can easily create a subvolume with 256 as its subvolumeid. Just create an empty fs, and create a new subvolume in it, then you got; item 11 key (256 ROOT_ITEM 0) itemoff 12961 itemsize 439 generation 7 root_dirid 256 bytenr 30441472 byte_limit 0 bytes_used 16384 ... So it's completely valid. The root cause is just snapshot creation conflicts with an existing qgroup. Thanks, Qu > > Reported-and-tested-by: syzbot+4d81015bc10889fd12ea@syzkaller.appspotmail.com > Fixes: 6ed05643ddb1 ("btrfs: create qgroup earlier in snapshot creation") > Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com> > --- > fs/btrfs/ioctl.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c > index 752acff2c734..21cf7a7f18ab 100644 > --- a/fs/btrfs/ioctl.c > +++ b/fs/btrfs/ioctl.c > @@ -3799,6 +3799,11 @@ static long btrfs_ioctl_qgroup_create(struct file *file, void __user *arg) > goto out; > } > > + if (sa->create && sa->qgroupid == BTRFS_FIRST_FREE_OBJECTID) { > + ret = -EINVAL; > + goto out; > + } > + > trans = btrfs_join_transaction(root); > if (IS_ERR(trans)) { > ret = PTR_ERR(trans);
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 752acff2c734..21cf7a7f18ab 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -3799,6 +3799,11 @@ static long btrfs_ioctl_qgroup_create(struct file *file, void __user *arg) goto out; } + if (sa->create && sa->qgroupid == BTRFS_FIRST_FREE_OBJECTID) { + ret = -EINVAL; + goto out; + } + trans = btrfs_join_transaction(root); if (IS_ERR(trans)) { ret = PTR_ERR(trans);
r0 = open(&(0x7f0000000080)='./file0\x00', 0x0, 0x0) ioctl$BTRFS_IOC_QUOTA_CTL(r0, 0xc0109428, &(0x7f0000000000)={0x1}) r1 = openat$cgroup_ro(0xffffffffffffff9c, &(0x7f0000000100)='blkio.bfq.time_recursive\x00', 0x275a, 0x0) ioctl$BTRFS_IOC_QGROUP_CREATE(r1, 0x4010942a, &(0x7f0000000640)={0x1, 0x100}) r2 = openat(0xffffffffffffff9c, &(0x7f0000000500)='.\x00', 0x0, 0x0) ioctl$BTRFS_IOC_SNAP_CREATE(r0, 0x50009401, &(0x7f0000000a80)={{r2}, From the logs, it can be seen that syz can execute to btrfs_ioctl_qgroup_create() through two paths. Syz enters btrfs_ioctl_qgroup_create() by calling ioctl$BTRFS_IOC_QGROUP_CREATE( r1, 0x4010942a,&(0x7f000000 640)={0x1, 0x100}) or ioctl$BTRFS_IOC_SNAP_CREATE(r0, 0x50009401,&(0x7f000000 a80)={r2}," respectively; The most crucial thing is that when calling ioctl$BTRFS_IOC_QGROUP_CREATE, the passed parameter qgroupid value is 256, while BTRFS_FIRST_FREE_OBJECTID is also equal to 256, indicating that the passed parameter qgroupid is obviously incorrect. Reported-and-tested-by: syzbot+4d81015bc10889fd12ea@syzkaller.appspotmail.com Fixes: 6ed05643ddb1 ("btrfs: create qgroup earlier in snapshot creation") Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com> --- fs/btrfs/ioctl.c | 5 +++++ 1 file changed, 5 insertions(+)