[PATCH 4.9 24/62] fs: ocfs2: fix possible null-pointer dereferences in ocfs2_xa_prepare_entry()

Greg Kroah-Hartman
2019-11-04T22:25:07Z

From: Jia-Ju Bai <baijiaju1990@gmail.com>

[ Upstream commit 56e94ea132bb5c2c1d0b60a6aeb34dcb7d71a53d ]

In ocfs2_xa_prepare_entry(), there is an if statement on line 2136 to
check whether loc->xl_entry is NULL:

if (loc->xl_entry)

When loc->xl_entry is NULL, it is used on line 2158:

ocfs2_xa_add_entry(loc, name_hash);
loc->xl_entry->xe_name_hash = cpu_to_le32(name_hash);
loc->xl_entry->xe_name_offset = cpu_to_le16(loc->xl_size);

and line 2164:

ocfs2_xa_add_namevalue(loc, xi);
loc->xl_entry->xe_value_size = cpu_to_le64(xi->xi_value_len);
loc->xl_entry->xe_name_len = xi->xi_name_len;

Thus, possible null-pointer dereferences may occur.

To fix these bugs, if loc-xl_entry is NULL, ocfs2_xa_prepare_entry()
abnormally returns with -EINVAL.

These bugs are found by a static analysis tool STCheck written by us.

[akpm@linux-foundation.org: remove now-unused ocfs2_xa_add_entry()]
Link: http://lkml.kernel.org/r/20190726101447.9153-1-baijiaju1990@gmail.com
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ocfs2/xattr.c | 56 ++++++++++++++++++++----------------------------
1 file changed, 23 insertions(+), 33 deletions(-)

diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index e108c945ac1f8..c387467d574cb 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -1497,18 +1497,6 @@ static int ocfs2_xa_check_space(struct ocfs2_xa_loc *loc,
return loc->xl_ops->xlo_check_space(loc, xi);
}

-static void ocfs2_xa_add_entry(struct ocfs2_xa_loc *loc, u32 name_hash)
-{
- loc->xl_ops->xlo_add_entry(loc, name_hash);
- loc->xl_entry->xe_name_hash = cpu_to_le32(name_hash);
- /*
- * We can't leave the new entry's xe_name_offset at zero or
- * add_namevalue() will go nuts. We set it to the size of our
- * storage so that it can never be less than any other entry.
- */
- loc->xl_entry->xe_name_offset = cpu_to_le16(loc->xl_size);
-}
-
static void ocfs2_xa_add_namevalue(struct ocfs2_xa_loc *loc,
struct ocfs2_xattr_info *xi)
{
@@ -2140,29 +2128,31 @@ static int ocfs2_xa_prepare_entry(struct ocfs2_xa_loc *loc,
if (rc)
goto out;

- if (loc->xl_entry) {
- if (ocfs2_xa_can_reuse_entry(loc, xi)) {
- orig_value_size = loc->xl_entry->xe_value_size;
- rc = ocfs2_xa_reuse_entry(loc, xi, ctxt);
- if (rc)
- goto out;
- goto alloc_value;
- }
+ if (!loc->xl_entry) {
+ rc = -EINVAL;
+ goto out;
+ }

- if (!ocfs2_xattr_is_local(loc->xl_entry)) {
- orig_clusters = ocfs2_xa_value_clusters(loc);
- rc = ocfs2_xa_value_truncate(loc, 0, ctxt);
- if (rc) {
- mlog_errno(rc);
- ocfs2_xa_cleanup_value_truncate(loc,
- "overwriting",
- orig_clusters);
- goto out;
- }
+ if (ocfs2_xa_can_reuse_entry(loc, xi)) {
+ orig_value_size = loc->xl_entry->xe_value_size;
+ rc = ocfs2_xa_reuse_entry(loc, xi, ctxt);
+ if (rc)
+ goto out;
+ goto alloc_value;
+ }
+
+ if (!ocfs2_xattr_is_local(loc->xl_entry)) {
+ orig_clusters = ocfs2_xa_value_clusters(loc);
+ rc = ocfs2_xa_value_truncate(loc, 0, ctxt);
+ if (rc) {
+ mlog_errno(rc);
+ ocfs2_xa_cleanup_value_truncate(loc,
+ "overwriting",
+ orig_clusters);
+ goto out;
}
- ocfs2_xa_wipe_namevalue(loc);
- } else
- ocfs2_xa_add_entry(loc, name_hash);
+ }
+ ocfs2_xa_wipe_namevalue(loc);

/*
* If we get here, we have a blank entry. Fill it. We grow our
--
2.20.1