linux-kernel - Re: [PATCH] fs/ntfs3: fix panic about slab-out-of-bounds caused by ntfs_list

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Message-ID: <34e1080f-6e87-5a9f-6a0b-5ce352a4b456@paragon-software.com>
Date:   Mon, 3 Jul 2023 11:36:57 +0400
From:   Konstantin Komarov <almaz.alexandrovich@...agon-software.com>
To:     Zeng Heng <zengheng4@...wei.com>
CC:     <weiyongjun1@...wei.com>, <xiexiuqi@...wei.com>,
        <ntfs3@...ts.linux.dev>, <liwei391@...wei.com>,
        <linux-kernel@...r.kernel.org>
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: syzbot+9fcea5ef6dc4dc72d334@...kaller.appspotmail.com
> Signed-off-by: Zeng Heng <zengheng4@...wei.com>
> ---
>   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.