diff options
| author | Gao Xiang <hsiangkao@redhat.com> | 2020-11-14 11:06:01 -0800 |
|---|---|---|
| committer | Darrick J. Wong <darrick.wong@oracle.com> | 2020-11-18 09:23:51 -0800 |
| commit | ada49d64fb3538144192181db05de17e2ffc3551 (patch) | |
| tree | 4330a5ad5f8d6cdfef9444790f54bfa8f190d3c7 /fs/xfs | |
| parent | 6b48e5b8a20f653b7d64ccf99a498f2523bff752 (diff) | |
xfs: fix forkoff miscalculation related to XFS_LITINO(mp)
Currently, commit e9e2eae89ddb dropped a (int) decoration from
XFS_LITINO(mp), and since sizeof() expression is also involved,
the result of XFS_LITINO(mp) is simply as the size_t type
(commonly unsigned long).
Considering the expression in xfs_attr_shortform_bytesfit():
offset = (XFS_LITINO(mp) - bytes) >> 3;
let "bytes" be (int)340, and
"XFS_LITINO(mp)" be (unsigned long)336.
on 64-bit platform, the expression is
offset = ((unsigned long)336 - (int)340) >> 3 =
(int)(0xfffffffffffffffcUL >> 3) = -1
but on 32-bit platform, the expression is
offset = ((unsigned long)336 - (int)340) >> 3 =
(int)(0xfffffffcUL >> 3) = 0x1fffffff
instead.
so offset becomes a large positive number on 32-bit platform, and
cause xfs_attr_shortform_bytesfit() returns maxforkoff rather than 0.
Therefore, one result is
"ASSERT(new_size <= XFS_IFORK_SIZE(ip, whichfork));"
assertion failure in xfs_idata_realloc(), which was also the root
cause of the original bugreport from Dennis, see:
https://bugzilla.redhat.com/show_bug.cgi?id=1894177
And it can also be manually triggered with the following commands:
$ touch a;
$ setfattr -n user.0 -v "`seq 0 80`" a;
$ setfattr -n user.1 -v "`seq 0 80`" a
on 32-bit platform.
Fix the case in xfs_attr_shortform_bytesfit() by bailing out
"XFS_LITINO(mp) < bytes" in advance suggested by Eric and a misleading
comment together with this bugfix suggested by Darrick. It seems the
other users of XFS_LITINO(mp) are not impacted.
Fixes: e9e2eae89ddb ("xfs: only check the superblock version for dinode size calculation")
Cc: <stable@vger.kernel.org> # 5.7+
Reported-and-tested-by: Dennis Gilmore <dgilmore@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Gao Xiang <hsiangkao@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')
| -rw-r--r-- | fs/xfs/libxfs/xfs_attr_leaf.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c index bb128db220ac..d6ef69ab1c67 100644 --- a/fs/xfs/libxfs/xfs_attr_leaf.c +++ b/fs/xfs/libxfs/xfs_attr_leaf.c @@ -515,7 +515,7 @@ xfs_attr_copy_value( *========================================================================*/ /* - * Query whether the requested number of additional bytes of extended + * Query whether the total requested number of attr fork bytes of extended * attribute space will be able to fit inline. * * Returns zero if not, else the di_forkoff fork offset to be used in the @@ -535,6 +535,12 @@ xfs_attr_shortform_bytesfit( int maxforkoff; int offset; + /* + * Check if the new size could fit at all first: + */ + if (bytes > XFS_LITINO(mp)) + return 0; + /* rounded down */ offset = (XFS_LITINO(mp) - bytes) >> 3; |