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authorGao Xiang <hsiangkao@redhat.com>2020-11-14 11:06:01 -0800
committerDarrick J. Wong <darrick.wong@oracle.com>2020-11-18 09:23:51 -0800
commitada49d64fb3538144192181db05de17e2ffc3551 (patch)
tree4330a5ad5f8d6cdfef9444790f54bfa8f190d3c7 /fs/xfs
parent6b48e5b8a20f653b7d64ccf99a498f2523bff752 (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.c8
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;