This is a note to let you know that I've just added the patch titled xfs: fix forkoff miscalculation related to XFS_LITINO(mp) to the 5.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: xfs-fix-forkoff-miscalculation-related-to-xfs_litino-mp.patch and it can be found in the queue-5.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From ada49d64fb3538144192181db05de17e2ffc3551 Mon Sep 17 00:00:00 2001 From: Gao Xiang <hsiangkao@xxxxxxxxxx> Date: Sat, 14 Nov 2020 11:06:01 -0800 Subject: xfs: fix forkoff miscalculation related to XFS_LITINO(mp) From: Gao Xiang <hsiangkao@xxxxxxxxxx> commit ada49d64fb3538144192181db05de17e2ffc3551 upstream. 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@xxxxxxxxxxxxxxx> # 5.7+ Reported-and-tested-by: Dennis Gilmore <dgilmore@xxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxx> Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/xfs/libxfs/xfs_attr_leaf.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) --- 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; Patches currently in stable-queue which might be from hsiangkao@xxxxxxxxxx are queue-5.9/xfs-fix-forkoff-miscalculation-related-to-xfs_litino-mp.patch