fs/ntfs3: fix panic about slab-out-of-bounds caused by ntfs_list_ea()

Here is a BUG report about linux-6.1 from syzbot, but it still remains
within upstream:

BUG: KASAN: slab-out-of-bounds in ntfs_list_ea fs/ntfs3/xattr.c:191 [inline]
BUG: KASAN: slab-out-of-bounds in ntfs_listxattr+0x401/0x570 fs/ntfs3/xattr.c:710
Read of size 1 at addr ffff888021acaf3d by task syz-executor128/3632

Call Trace:
 kasan_report+0x139/0x170 mm/kasan/report.c:495
 ntfs_list_ea fs/ntfs3/xattr.c:191 [inline]
 ntfs_listxattr+0x401/0x570 fs/ntfs3/xattr.c:710
 vfs_listxattr fs/xattr.c:457 [inline]
 listxattr+0x293/0x2d0 fs/xattr.c:804
 path_listxattr fs/xattr.c:828 [inline]
 __do_sys_llistxattr fs/xattr.c:846 [inline]

Before derefering field members of `ea` in unpacked_ea_size(), we need to
check whether the EA_FULL struct is located in access validate range.

Similarly, when derefering `ea->name` field member, we need to check
whethe the ea->name is located in access validate range, too.

Fixes: be71b5cba2e6 ("fs/ntfs3: Add attrib operations")
Reported-by: syzbot+9fcea5ef6dc4dc72d334@syzkaller.appspotmail.com
Signed-off-by: Zeng Heng <zengheng4@huawei.com>
[almaz.alexandrovich@paragon-software.com: took the ret variable out of the loop block]
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

diff --git a/fs/ntfs3/xattr.c b/fs/ntfs3/xattr.c
index 29fd391899e59dfde9b29e920f7303862b7167ff..4920548192a0cf3513060717194e0e57c94452f9 100644 (file)
--- a/fs/ntfs3/xattr.c
+++ b/fs/ntfs3/xattr.c
@@ -211,7 +211,8 @@ static ssize_t ntfs_list_ea(struct ntfs_inode *ni, char *buffer,
        size = le32_to_cpu(info->size);
 
        /* Enumerate all xattrs. */
-       for (ret = 0, off = 0; off < size; off += ea_size) {
+       ret = 0;
+       for (off = 0; off + sizeof(struct EA_FULL) < size; off += ea_size) {
                ea = Add2Ptr(ea_all, off);
                ea_size = unpacked_ea_size(ea);
 
@@ -219,6 +220,10 @@ static ssize_t ntfs_list_ea(struct ntfs_inode *ni, char *buffer,
                        break;
 
                if (buffer) {
+                       /* Check if we can use field ea->name */
+                       if (off + ea_size > size)
+                               break;
+
                        if (ret + ea->name_len + 1 > bytes_per_buffer) {
                                err = -ERANGE;
                                goto out;