When adding an xattr to an inode, we must ensure that the inode_size is
not less than EXT4_GOOD_OLD_INODE_SIZE + extra_isize + pad. Otherwise,
the end position may be greater than the start position, resulting in UAF.
Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>
---
fs/ext4/xattr.h | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h
index 77efb9a627ad..f885f362add4 100644
--- a/fs/ext4/xattr.h
+++ b/fs/ext4/xattr.h
@@ -95,6 +95,19 @@ struct ext4_xattr_entry {
#define EXT4_ZERO_XATTR_VALUE ((void *)-1)
+/*
+ * If we want to add an xattr to the inode, we should make sure that
+ * i_extra_isize is not 0 and that the inode size is not less than
+ * EXT4_GOOD_OLD_INODE_SIZE + extra_isize + pad.
+ * EXT4_GOOD_OLD_INODE_SIZE extra_isize header entry pad data
+ * |--------------------------|------------|------|---------|---|-------|
+ */
+#define EXT4_INODE_HAS_XATTR_SPACE(inode) \
+ ((EXT4_I(inode)->i_extra_isize != 0) && \
+ (EXT4_GOOD_OLD_INODE_SIZE + EXT4_I(inode)->i_extra_isize + \
+ sizeof(struct ext4_xattr_ibody_header) + EXT4_XATTR_PAD <= \
+ EXT4_INODE_SIZE((inode)->i_sb)))
+
struct ext4_xattr_info {
const char *name;
const void *value;
--
2.31.1
