[PATCH AUTOSEL 5.9 085/147] xfs: avoid LR buffer overrun due to crafted h_len

Sasha Levin
2020-10-27T00:41:13Z

From: Gao Xiang <hsiangkao@redhat.com>

[ Upstream commit f692d09e9c8fd0f5557c2e87f796a16dd95222b8 ]

Currently, crafted h_len has been blocked for the log
header of the tail block in commit a70f9fe52daa ("xfs:
detect and handle invalid iclog size set by mkfs").

However, each log record could still have crafted h_len
and cause log record buffer overrun. So let's check
h_len vs buffer size for each log record as well.

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>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/xfs/xfs_log_recover.c | 39 +++++++++++++++++++--------------------
1 file changed, 19 insertions(+), 20 deletions(-)

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index e2ec91b2d0f46..9ceb67d0f2565 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -2904,7 +2904,8 @@ STATIC int
xlog_valid_rec_header(
struct xlog *log,
struct xlog_rec_header *rhead,
- xfs_daddr_t blkno)
+ xfs_daddr_t blkno,
+ int bufsize)
{
int hlen;

@@ -2920,10 +2921,14 @@ xlog_valid_rec_header(
return -EFSCORRUPTED;
}

- /* LR body must have data or it wouldn't have been written */
+ /*
+ * LR body must have data (or it wouldn't have been written)
+ * and h_len must not be greater than LR buffer size.
+ */
hlen = be32_to_cpu(rhead->h_len);
- if (XFS_IS_CORRUPT(log->l_mp, hlen <= 0 || hlen > INT_MAX))
+ if (XFS_IS_CORRUPT(log->l_mp, hlen <= 0 || hlen > bufsize))
return -EFSCORRUPTED;
+
if (XFS_IS_CORRUPT(log->l_mp,
blkno > log->l_logBBsize || blkno > INT_MAX))
return -EFSCORRUPTED;
@@ -2984,9 +2989,6 @@ xlog_do_recovery_pass(
goto bread_err1;

rhead = (xlog_rec_header_t *)offset;
- error = xlog_valid_rec_header(log, rhead, tail_blk);
- if (error)
- goto bread_err1;

/*
* xfsprogs has a bug where record length is based on lsunit but
@@ -3001,21 +3003,18 @@ xlog_do_recovery_pass(
*/
h_size = be32_to_cpu(rhead->h_size);
h_len = be32_to_cpu(rhead->h_len);
- if (h_len > h_size) {
- if (h_len <= log->l_mp->m_logbsize &&
- be32_to_cpu(rhead->h_num_logops) == 1) {
- xfs_warn(log->l_mp,
+ if (h_len > h_size && h_len <= log->l_mp->m_logbsize &&
+ rhead->h_num_logops == cpu_to_be32(1)) {
+ xfs_warn(log->l_mp,
"invalid iclog size (%d bytes), using lsunit (%d bytes)",
- h_size, log->l_mp->m_logbsize);
- h_size = log->l_mp->m_logbsize;
- } else {
- XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW,
- log->l_mp);
- error = -EFSCORRUPTED;
- goto bread_err1;
- }
+ h_size, log->l_mp->m_logbsize);
+ h_size = log->l_mp->m_logbsize;
}

+ error = xlog_valid_rec_header(log, rhead, tail_blk, h_size);
+ if (error)
+ goto bread_err1;
+
if ((be32_to_cpu(rhead->h_version) & XLOG_VERSION_2) &&
(h_size > XLOG_HEADER_CYCLE_SIZE)) {
hblks = h_size / XLOG_HEADER_CYCLE_SIZE;
@@ -3096,7 +3095,7 @@ xlog_do_recovery_pass(
}
rhead = (xlog_rec_header_t *)offset;
error = xlog_valid_rec_header(log, rhead,
- split_hblks ? blk_no : 0);
+ split_hblks ? blk_no : 0, h_size);
if (error)
goto bread_err2;

@@ -3177,7 +3176,7 @@ xlog_do_recovery_pass(
goto bread_err2;

rhead = (xlog_rec_header_t *)offset;
- error = xlog_valid_rec_header(log, rhead, blk_no);
+ error = xlog_valid_rec_header(log, rhead, blk_no, h_size);
if (error)
goto bread_err2;

--
2.25.1