From: Christoph Hellwig hch@lst.de

[ Upstream commit 45cf976008ddef4a9c9a30310c9b4fb2a9a6602a ]

Note: The upstream commit was adjusted to use kmem_free instead of kvfree since kmem_free was used in xfs_log_recover.c until commit 49292576136f (xfs: convert kmem_free() for kvmalloc users to kvfree()), and the remainder of the file still uses kmem_free.

Commit a70f9fe52daa ("xfs: detect and handle invalid iclog size set by mkfs") added a fixup for incorrect h_size values used for the initial umount record in old xfsprogs versions. Later commit 0c771b99d6c9 ("xfs: clean up calculation of LR header blocks") cleaned up the log reover buffer calculation, but stoped using the fixed up h_size value to size the log recovery buffer, which can lead to an out of bounds access when the incorrect h_size does not come from the old mkfs tool, but a fuzzer.

Fix this by open coding xlog_logrec_hblks and taking the fixed h_size into account for this calculation.

Fixes: 0c771b99d6c9 ("xfs: clean up calculation of LR header blocks") Reported-by: Sam Sun samsun1006219@gmail.com Signed-off-by: Christoph Hellwig hch@lst.de Reviewed-by: Brian Foster bfoster@redhat.com Reviewed-by: "Darrick J. Wong" djwong@kernel.org Signed-off-by: Chandan Babu R chandanbabu@kernel.org Signed-off-by: Kevin Berry kpberry@google.com --- fs/xfs/xfs_log_recover.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c index 57f366c3d355..9f9d3abad2cf 100644 --- a/fs/xfs/xfs_log_recover.c +++ b/fs/xfs/xfs_log_recover.c @@ -2965,7 +2965,7 @@ xlog_do_recovery_pass( int error = 0, h_size, h_len; int error2 = 0; int bblks, split_bblks; - int hblks, split_hblks, wrapped_hblks; + int hblks = 1, split_hblks, wrapped_hblks; int i; struct hlist_head rhash[XLOG_RHASH_SIZE]; LIST_HEAD (buffer_list); @@ -3021,14 +3021,22 @@ xlog_do_recovery_pass( if (error) goto bread_err1;

- hblks = xlog_logrec_hblks(log, rhead); - if (hblks != 1) { - kmem_free(hbp); - hbp = xlog_alloc_buffer(log, hblks); + /* + * This open codes xlog_logrec_hblks so that we can reuse the + * fixed up h_size value calculated above. Without that we'd + * still allocate the buffer based on the incorrect on-disk + * size. + */ + if (h_size > XLOG_HEADER_CYCLE_SIZE && + (rhead->h_version & cpu_to_be32(XLOG_VERSION_2))) { + hblks = DIV_ROUND_UP(h_size, XLOG_HEADER_CYCLE_SIZE); + if (hblks > 1) { + kmem_free(hbp); + hbp = xlog_alloc_buffer(log, hblks); + } } } else { ASSERT(log->l_sectBBsize == 1); - hblks = 1; hbp = xlog_alloc_buffer(log, 1); h_size = XLOG_BIG_RECORD_BSIZE; }