Re: [PATCH] fs/ntfs3: Fix slab-out-of-bounds read in hdr_delete_de()

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On 12.12.2022 05:31, Zeng Heng wrote:
Here is a BUG report from syzbot:

BUG: KASAN: slab-out-of-bounds in hdr_delete_de+0xe0/0x150 fs/ntfs3/index.c:806
Read of size 16842960 at addr ffff888079cc0600 by task syz-executor934/3631

Call Trace:
  memmove+0x25/0x60 mm/kasan/shadow.c:54
  hdr_delete_de+0xe0/0x150 fs/ntfs3/index.c:806
  indx_delete_entry+0x74f/0x3670 fs/ntfs3/index.c:2193
  ni_remove_name+0x27a/0x980 fs/ntfs3/frecord.c:2910
  ntfs_unlink_inode+0x3d4/0x720 fs/ntfs3/inode.c:1712
  ntfs_rename+0x41a/0xcb0 fs/ntfs3/namei.c:276

Before using the meta-data in struct INDEX_HDR, we need to
check index header valid or not. Otherwise, the corruptedi
(or malicious) fs image can cause out-of-bounds access which
could make kernel panic.

Fixes: 82cae269cfa9 ("fs/ntfs3: Add initialization of super block")
Reported-by: syzbot+9c2811fd56591639ff5f@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Zeng Heng <zengheng4@xxxxxxxxxx>
---
  fs/ntfs3/fslog.c   | 2 +-
  fs/ntfs3/index.c   | 4 ++++
  fs/ntfs3/ntfs_fs.h | 1 +
  3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/ntfs3/fslog.c b/fs/ntfs3/fslog.c
index 0d611a6c5511..0de2bbb42721 100644
--- a/fs/ntfs3/fslog.c
+++ b/fs/ntfs3/fslog.c
@@ -2597,7 +2597,7 @@ static int read_next_log_rec(struct ntfs_log *log, struct lcb *lcb, u64 *lsn)
  	return find_log_rec(log, *lsn, lcb);
  }
-static inline bool check_index_header(const struct INDEX_HDR *hdr, size_t bytes)
+bool check_index_header(const struct INDEX_HDR *hdr, size_t bytes)
  {
  	__le16 mask;
  	u32 min_de, de_off, used, total;
diff --git a/fs/ntfs3/index.c b/fs/ntfs3/index.c
index 440328147e7e..6f5d8dd6659d 100644
--- a/fs/ntfs3/index.c
+++ b/fs/ntfs3/index.c
@@ -798,6 +798,10 @@ static inline struct NTFS_DE *hdr_delete_de(struct INDEX_HDR *hdr,
  	u32 off = PtrOffset(hdr, re);
  	int bytes = used - (off + esize);
+ /* check INDEX_HDR valid before using INDEX_HDR */
+	if (!check_index_header(hdr, le32_to_cpu(hdr->total)))
+		return NULL;
+
  	if (off >= used || esize < sizeof(struct NTFS_DE) ||
  	    bytes < sizeof(struct NTFS_DE))
  		return NULL;
diff --git a/fs/ntfs3/ntfs_fs.h b/fs/ntfs3/ntfs_fs.h
index 2c791222c4e2..c5c022fef4e0 100644
--- a/fs/ntfs3/ntfs_fs.h
+++ b/fs/ntfs3/ntfs_fs.h
@@ -574,6 +574,7 @@ int ni_rename(struct ntfs_inode *dir_ni, struct ntfs_inode *new_dir_ni,
  bool ni_is_dirty(struct inode *inode);
/* Globals from fslog.c */
+bool check_index_header(const struct INDEX_HDR *hdr, size_t bytes);
  int log_replay(struct ntfs_inode *ni, bool *initialized);
/* Globals from fsntfs.c */
Thanks for patch, applied!




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