From: Gao Xiang Date: Mon, 23 Nov 2020 19:25:15 +0000 (-0500) Subject: xfs: fix forkoff miscalculation related to XFS_LITINO(mp) X-Git-Tag: xfsprogs-5.10-fixes_2020-12-06~7 X-Git-Url: http://git.ipfire.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=7ec359998d2802e75bc2754e305cd64b58658932;p=thirdparty%2Fxfsprogs-dev.git xfs: fix forkoff miscalculation related to XFS_LITINO(mp) Source kernel commit: ada49d64fb3538144192181db05de17e2ffc3551 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: # 5.7+ Reported-and-tested-by: Dennis Gilmore Reviewed-by: Christoph Hellwig Signed-off-by: Gao Xiang Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Signed-off-by: Eric Sandeen --- diff --git a/libxfs/xfs_attr_leaf.c b/libxfs/xfs_attr_leaf.c index 08117446b..a59660f23 100644 --- a/libxfs/xfs_attr_leaf.c +++ b/libxfs/xfs_attr_leaf.c @@ -512,7 +512,7 @@ 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 @@ -532,6 +532,12 @@ 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;