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Subject[PATCH 1/3 v2] fs: ocfs2: Fix possible null-pointer dereferences in ocfs2_xa_prepare_entry()
Date
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.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
v2:
* Directly return -EINVAL if loc-xl_entry is NULL.
Thank Joseph for helpful advice.

---
fs/ocfs2/xattr.c | 44 +++++++++++++++++++++++---------------------
1 file changed, 23 insertions(+), 21 deletions(-)

diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index 385f3aaa2448..4b876c82a35c 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -2133,29 +2133,31 @@ 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
--
2.17.0
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