From: "Darrick J. Wong" djwong@kernel.org
commit 38de567906d95c397d87f292b892686b7ec6fbc3 upstream.
An internal user complained about log recovery failing on a symlink ("Bad dinode after recovery") with the following (excerpted) format:
core.magic = 0x494e core.mode = 0120777 core.version = 3 core.format = 2 (extents) core.nlinkv2 = 1 core.nextents = 1 core.size = 297 core.nblocks = 1 core.naextents = 0 core.forkoff = 0 core.aformat = 2 (extents) u3.bmx[0] = [startoff,startblock,blockcount,extentflag] 0:[0,12,1,0]
This is a symbolic link with a 297-byte target stored in a disk block, which is to say this is a symlink with a remote target. The forkoff is 0, which is to say that there's 512 - 176 == 336 bytes in the inode core to store the data fork.
Eventually, testing of generic/388 failed with the same inode corruption message during inode recovery. In writing a debugging patch to call xfs_dinode_verify on dirty inode log items when we're committing transactions, I observed that xfs/298 can reproduce the problem quite quickly.
xfs/298 creates a symbolic link, adds some extended attributes, then deletes them all. The test failure occurs when the final removexattr also deletes the attr fork because that does not convert the remote symlink back into a shortform symlink. That is how we trip this test. The only reason why xfs/298 only triggers with the debug patch added is that it deletes the symlink, so the final iflush shows the inode as free.
I wrote a quick fstest to emulate the behavior of xfs/298, except that it leaves the symlinks on the filesystem after inducing the "corrupt" state. Kernels going back at least as far as 4.18 have written out symlink inodes in this manner and prior to 1eb70f54c445f they did not object to reading them back in.
Because we've been writing out inodes this way for quite some time, the only way to fix this is to relax the check for symbolic links. Directories don't have this problem because di_size is bumped to blocksize during the sf->data conversion.
Fixes: 1eb70f54c445f ("xfs: validate inode fork size against fork format") Signed-off-by: "Darrick J. Wong" djwong@kernel.org Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Chandan Babu R chandanbabu@kernel.org Signed-off-by: Catherine Hoang catherine.hoang@oracle.com Acked-by: Darrick J. Wong djwong@kernel.org --- fs/xfs/libxfs/xfs_inode_buf.c | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-)
diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c index 0f970a0b3382..51fdd29c4ddc 100644 --- a/fs/xfs/libxfs/xfs_inode_buf.c +++ b/fs/xfs/libxfs/xfs_inode_buf.c @@ -366,17 +366,37 @@ xfs_dinode_verify_fork( /* * For fork types that can contain local data, check that the fork * format matches the size of local data contained within the fork. - * - * For all types, check that when the size says the should be in extent - * or btree format, the inode isn't claiming it is in local format. */ if (whichfork == XFS_DATA_FORK) { - if (S_ISDIR(mode) || S_ISLNK(mode)) { + /* + * A directory small enough to fit in the inode must be stored + * in local format. The directory sf <-> extents conversion + * code updates the directory size accordingly. + */ + if (S_ISDIR(mode)) { + if (be64_to_cpu(dip->di_size) <= fork_size && + fork_format != XFS_DINODE_FMT_LOCAL) + return __this_address; + } + + /* + * A symlink with a target small enough to fit in the inode can + * be stored in extents format if xattrs were added (thus + * converting the data fork from shortform to remote format) + * and then removed. + */ + if (S_ISLNK(mode)) { if (be64_to_cpu(dip->di_size) <= fork_size && + fork_format != XFS_DINODE_FMT_EXTENTS && fork_format != XFS_DINODE_FMT_LOCAL) return __this_address; }
+ /* + * For all types, check that when the size says the fork should + * be in extent or btree format, the inode isn't claiming to be + * in local format. + */ if (be64_to_cpu(dip->di_size) > fork_size && fork_format == XFS_DINODE_FMT_LOCAL) return __this_address;