diff options
author | Eric Sandeen <sandeen@sandeen.net> | 2016-11-08 01:55:18 (GMT) |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-01-06 09:40:17 (GMT) |
commit | c11a13d6f5274167a7c44e08722162ae3acce437 (patch) | |
tree | a0f1e4323b9f8299cbbab6748621a1354041dd44 /fs/xfs/xfs_bmap_util.c | |
parent | e67053ad4840676f34215823770ba6d95037d138 (diff) | |
download | linux-c11a13d6f5274167a7c44e08722162ae3acce437.tar.xz |
xfs: fix up xfs_swap_extent_forks inline extent handling
commit 4dfce57db6354603641132fac3c887614e3ebe81 upstream.
There have been several reports over the years of NULL pointer
dereferences in xfs_trans_log_inode during xfs_fsr processes,
when the process is doing an fput and tearing down extents
on the temporary inode, something like:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
PID: 29439 TASK: ffff880550584fa0 CPU: 6 COMMAND: "xfs_fsr"
[exception RIP: xfs_trans_log_inode+0x10]
#9 [ffff8800a57bbbe0] xfs_bunmapi at ffffffffa037398e [xfs]
#10 [ffff8800a57bbce8] xfs_itruncate_extents at ffffffffa0391b29 [xfs]
#11 [ffff8800a57bbd88] xfs_inactive_truncate at ffffffffa0391d0c [xfs]
#12 [ffff8800a57bbdb8] xfs_inactive at ffffffffa0392508 [xfs]
#13 [ffff8800a57bbdd8] xfs_fs_evict_inode at ffffffffa035907e [xfs]
#14 [ffff8800a57bbe00] evict at ffffffff811e1b67
#15 [ffff8800a57bbe28] iput at ffffffff811e23a5
#16 [ffff8800a57bbe58] dentry_kill at ffffffff811dcfc8
#17 [ffff8800a57bbe88] dput at ffffffff811dd06c
#18 [ffff8800a57bbea8] __fput at ffffffff811c823b
#19 [ffff8800a57bbef0] ____fput at ffffffff811c846e
#20 [ffff8800a57bbf00] task_work_run at ffffffff81093b27
#21 [ffff8800a57bbf30] do_notify_resume at ffffffff81013b0c
#22 [ffff8800a57bbf50] int_signal at ffffffff8161405d
As it turns out, this is because the i_itemp pointer, along
with the d_ops pointer, has been overwritten with zeros
when we tear down the extents during truncate. When the in-core
inode fork on the temporary inode used by xfs_fsr was originally
set up during the extent swap, we mistakenly looked at di_nextents
to determine whether all extents fit inline, but this misses extents
generated by speculative preallocation; we should be using if_bytes
instead.
This mistake corrupts the in-memory inode, and code in
xfs_iext_remove_inline eventually gets bad inputs, causing
it to memmove and memset incorrect ranges; this became apparent
because the two values in ifp->if_u2.if_inline_ext[1] contained
what should have been in d_ops and i_itemp; they were memmoved due
to incorrect array indexing and then the original locations
were zeroed with memset, again due to an array overrun.
Fix this by properly using i_df.if_bytes to determine the number
of extents, not di_nextents.
Thanks to dchinner for looking at this with me and spotting the
root cause.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/xfs/xfs_bmap_util.c')
-rw-r--r-- | fs/xfs/xfs_bmap_util.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c index 552465e..47074e0c 100644 --- a/fs/xfs/xfs_bmap_util.c +++ b/fs/xfs/xfs_bmap_util.c @@ -1792,6 +1792,7 @@ xfs_swap_extent_forks( struct xfs_ifork tempifp, *ifp, *tifp; int aforkblks = 0; int taforkblks = 0; + xfs_extnum_t nextents; __uint64_t tmp; int error; @@ -1881,7 +1882,8 @@ xfs_swap_extent_forks( * pointer. Otherwise it's already NULL or * pointing to the extent. */ - if (ip->i_d.di_nextents <= XFS_INLINE_EXTS) { + nextents = ip->i_df.if_bytes / (uint)sizeof(xfs_bmbt_rec_t); + if (nextents <= XFS_INLINE_EXTS) { ifp->if_u1.if_extents = ifp->if_u2.if_inline_ext; } @@ -1900,7 +1902,8 @@ xfs_swap_extent_forks( * pointer. Otherwise it's already NULL or * pointing to the extent. */ - if (tip->i_d.di_nextents <= XFS_INLINE_EXTS) { + nextents = tip->i_df.if_bytes / (uint)sizeof(xfs_bmbt_rec_t); + if (nextents <= XFS_INLINE_EXTS) { tifp->if_u1.if_extents = tifp->if_u2.if_inline_ext; } |