2023-04-20 07:21:20

by Zeng Heng

Subject: [PATCH] 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: [email protected]
Signed-off-by: Zeng Heng <[email protected]>
---
fs/ntfs3/xattr.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/ntfs3/xattr.c b/fs/ntfs3/xattr.c
index ff64302e87e5..27eb30453b9f 100644
--- a/fs/ntfs3/xattr.c
+++ b/fs/ntfs3/xattr.c
@@ -210,11 +210,15 @@ 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) {
+ for (ret = 0, off = 0; off + sizeof(struct EA_FULL) < size; off += ea_size) {
ea = Add2Ptr(ea_all, off);
ea_size = unpacked_ea_size(ea);

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;
--
2.25.1

2023-07-03 07:45:47

by Konstantin Komarov

Subject: Re: [PATCH] fs/ntfs3: fix panic about slab-out-of-bounds caused by ntfs_list_ea()

On 20.04.2023 11:46, Zeng Heng wrote:
> 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: [email protected]
> Signed-off-by: Zeng Heng <[email protected]>
> ---
> fs/ntfs3/xattr.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ntfs3/xattr.c b/fs/ntfs3/xattr.c
> index ff64302e87e5..27eb30453b9f 100644
> --- a/fs/ntfs3/xattr.c
> +++ b/fs/ntfs3/xattr.c
> @@ -210,11 +210,15 @@ 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) {
> + for (ret = 0, off = 0; off + sizeof(struct EA_FULL) < size; off += ea_size) {
> ea = Add2Ptr(ea_all, off);
> ea_size = unpacked_ea_size(ea);
>
> 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;
Thanks, your patch has been applied.