diff options
| author | Richard Wareing <rwareing@fb.com> | 2017-09-13 09:09:35 +1000 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-09-12 20:02:22 -0700 |
| commit | b31ff3cdf540110da4572e3e29bd172087af65cc (patch) | |
| tree | 8fedc3252527ea0df94c4a8feca77f3e99473d56 /fs | |
| parent | 52269718dc2cf2585d7a2828f31d46ef46e68000 (diff) | |
xfs: XFS_IS_REALTIME_INODE() should be false if no rt device present
If using a kernel with CONFIG_XFS_RT=y and we set the RHINHERIT flag on
a directory in a filesystem that does not have a realtime device and
create a new file in that directory, it gets marked as a real time file.
When data is written and a fsync is issued, the filesystem attempts to
flush a non-existent rt device during the fsync process.
This results in a crash dereferencing a null buftarg pointer in
xfs_blkdev_issue_flush():
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
IP: xfs_blkdev_issue_flush+0xd/0x20
.....
Call Trace:
xfs_file_fsync+0x188/0x1c0
vfs_fsync_range+0x3b/0xa0
do_fsync+0x3d/0x70
SyS_fsync+0x10/0x20
do_syscall_64+0x4d/0xb0
entry_SYSCALL64_slow_path+0x25/0x25
Setting RT inode flags does not require special privileges so any
unprivileged user can cause this oops to occur. To reproduce, confirm
kernel is compiled with CONFIG_XFS_RT=y and run:
# mkfs.xfs -f /dev/pmem0
# mount /dev/pmem0 /mnt/test
# mkdir /mnt/test/foo
# xfs_io -c 'chattr +t' /mnt/test/foo
# xfs_io -f -c 'pwrite 0 5m' -c fsync /mnt/test/foo/bar
Or just run xfstests with MKFS_OPTIONS="-d rtinherit=1" and wait.
Kernels built with CONFIG_XFS_RT=n are not exposed to this bug.
Fixes: f538d4da8d52 ("[XFS] write barrier support")
Cc: <stable@vger.kernel.org>
Signed-off-by: Richard Wareing <rwareing@fb.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/xfs/xfs_linux.h | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/fs/xfs/xfs_linux.h b/fs/xfs/xfs_linux.h index 9301c5a6060b..dcd1292664b3 100644 --- a/fs/xfs/xfs_linux.h +++ b/fs/xfs/xfs_linux.h @@ -270,7 +270,14 @@ static inline uint64_t howmany_64(uint64_t x, uint32_t y) #endif /* DEBUG */ #ifdef CONFIG_XFS_RT -#define XFS_IS_REALTIME_INODE(ip) ((ip)->i_d.di_flags & XFS_DIFLAG_REALTIME) + +/* + * make sure we ignore the inode flag if the filesystem doesn't have a + * configured realtime device. + */ +#define XFS_IS_REALTIME_INODE(ip) \ + (((ip)->i_d.di_flags & XFS_DIFLAG_REALTIME) && \ + (ip)->i_mount->m_rtdev_targp) #else #define XFS_IS_REALTIME_INODE(ip) (0) #endif |