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author | 2019-03-17 15:21:49 -0700 | |
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committer | 2019-03-17 15:21:49 -0700 | |
commit | 6958d11f77d45db80f7e22a21a74d4d5f44dc667 (patch) | |
tree | 5fb752c90dc51c6bc8b277e12b6d40edb9cea2c4 /fs/xfs/libxfs/xfs_bmap.c | |
parent | Linux 5.1-rc1 (diff) | |
download | linux-6958d11f77d45db80f7e22a21a74d4d5f44dc667.tar.gz linux-6958d11f77d45db80f7e22a21a74d4d5f44dc667.tar.bz2 linux-6958d11f77d45db80f7e22a21a74d4d5f44dc667.zip |
xfs: don't trip over uninitialized buffer on extent read of corrupted inode
We've had rather rare reports of bmap btree block corruption where
the bmap root block has a level count of zero. The root cause of the
corruption is so far unknown. We do have verifier checks to detect
this form of on-disk corruption, but this doesn't cover a memory
corruption variant of the problem. The latter is a reasonable
possibility because the root block is part of the inode fork and can
reside in-core for some time before inode extents are read.
If this occurs, it leads to a system crash such as the following:
BUG: unable to handle kernel paging request at ffffffff00000221
PF error: [normal kernel read fault]
...
RIP: 0010:xfs_trans_brelse+0xf/0x200 [xfs]
...
Call Trace:
xfs_iread_extents+0x379/0x540 [xfs]
xfs_file_iomap_begin_delay+0x11a/0xb40 [xfs]
? xfs_attr_get+0xd1/0x120 [xfs]
? iomap_write_begin.constprop.40+0x2d0/0x2d0
xfs_file_iomap_begin+0x4c4/0x6d0 [xfs]
? __vfs_getxattr+0x53/0x70
? iomap_write_begin.constprop.40+0x2d0/0x2d0
iomap_apply+0x63/0x130
? iomap_write_begin.constprop.40+0x2d0/0x2d0
iomap_file_buffered_write+0x62/0x90
? iomap_write_begin.constprop.40+0x2d0/0x2d0
xfs_file_buffered_aio_write+0xe4/0x3b0 [xfs]
__vfs_write+0x150/0x1b0
vfs_write+0xba/0x1c0
ksys_pwrite64+0x64/0xa0
do_syscall_64+0x5a/0x1d0
entry_SYSCALL_64_after_hwframe+0x49/0xbe
The crash occurs because xfs_iread_extents() attempts to release an
uninitialized buffer pointer as the level == 0 value prevented the
buffer from ever being allocated or read. Change the level > 0
assert to an explicit error check in xfs_iread_extents() to avoid
crashing the kernel in the event of localized, in-core inode
corruption.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'fs/xfs/libxfs/xfs_bmap.c')
-rw-r--r-- | fs/xfs/libxfs/xfs_bmap.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index 48502cb9990f..ae4c3b0d84db 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -1191,7 +1191,10 @@ xfs_iread_extents( * Root level must use BMAP_BROOT_PTR_ADDR macro to get ptr out. */ level = be16_to_cpu(block->bb_level); - ASSERT(level > 0); + if (unlikely(level == 0)) { + XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, mp); + return -EFSCORRUPTED; + } pp = XFS_BMAP_BROOT_PTR_ADDR(mp, block, 1, ifp->if_broot_bytes); bno = be64_to_cpu(*pp); |