2022-12-07 16:52:02

by Zeng Heng

Subject: [PATCH] ntfs: fix panic about slab-out-of-bounds caused by ntfs_listxattr()

Here is a BUG report from syzbot:

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:
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

Fix the logic of ea_all iteration. When the ea->name_len is 0,
return immediately, or Add2Ptr() would visit invalid memory
in the next loop.

Fixes: be71b5cba2e6 ("fs/ntfs3: Add attrib operations")
Reported-by: [email protected]
Signed-off-by: Zeng Heng <[email protected]>
---
fs/ntfs3/xattr.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/fs/ntfs3/xattr.c b/fs/ntfs3/xattr.c
index 7de8718c68a9..911e110b8d6e 100644
--- a/fs/ntfs3/xattr.c
+++ b/fs/ntfs3/xattr.c
@@ -178,6 +178,9 @@ static ssize_t ntfs_list_ea(struct ntfs_inode *ni, char *buffer,
for (ret = 0, off = 0; off < size; off += unpacked_ea_size(ea)) {
ea = Add2Ptr(ea_all, off);

+ if (!ea->name_len)
+ break;
+
if (buffer) {
if (ret + ea->name_len + 1 > bytes_per_buffer) {
err = -ERANGE;
--
2.25.1

2023-01-10 11:10:09

by Zeng Heng

Subject: Re: [PATCH] ntfs: fix panic about slab-out-of-bounds caused by ntfs_listxattr()

On 2022/12/8 0:28, Zeng Heng wrote:
> Here is a BUG report from syzbot:
>
> 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:
> 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
>
> Fix the logic of ea_all iteration. When the ea->name_len is 0,
> return immediately, or Add2Ptr() would visit invalid memory
> in the next loop.
>
> Fixes: be71b5cba2e6 ("fs/ntfs3: Add attrib operations")
> Reported-by: [email protected]
> Signed-off-by: Zeng Heng <[email protected]>
> ---
> fs/ntfs3/xattr.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/fs/ntfs3/xattr.c b/fs/ntfs3/xattr.c
> index 7de8718c68a9..911e110b8d6e 100644
> --- a/fs/ntfs3/xattr.c
> +++ b/fs/ntfs3/xattr.c
> @@ -178,6 +178,9 @@ static ssize_t ntfs_list_ea(struct ntfs_inode *ni, char *buffer,
> for (ret = 0, off = 0; off < size; off += unpacked_ea_size(ea)) {
> ea = Add2Ptr(ea_all, off);
>
> + if (!ea->name_len)
> + break;
> +
> if (buffer) {
> if (ret + ea->name_len + 1 > bytes_per_buffer) {
> err = -ERANGE;

Is there any comment about this patch?

Thanks for advance.


Zeng Heng