From 62656b024efc21c3230eade1a847f25871c3d2bb Mon Sep 17 00:00:00 2001 From: Frank Sorenson Date: Mon, 17 Aug 2026 12:16:51 -0500 Subject: [PATCH] smb: client: fix ALIGN() overflow in symlink_data() error context loop The check added by commit 7d9a7f1f96cd ("smb/client: fix possible infinite loop and oob read in symlink_data()") compared the post-ALIGN length against the remaining buffer, but ALIGN() itself can overflow: for ErrorDataLength near UINT32_MAX (e.g. 0xFFFFFFF9), ALIGN(x, 8) wraps to 0, so the subsequent bounds check passes, and the loop advances by zero bytes leaving 'p' pointing into stale data. Fix by checking the raw ErrorDataLength against the remaining space before applying ALIGN(), then checking again after. Since raw_len is bounded by the buffer, raw_len + 7 cannot overflow, so the second check is an exact post-alignment bounds guard. Fixes: 76894f3e2f71 ("cifs: improve symlink handling for smb2+") Cc: stable@vger.kernel.org Signed-off-by: Frank Sorenson Signed-off-by: Namjae Jeon Signed-off-by: Paulo Alcantara --- fs/smb/client/smb2file.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/smb/client/smb2file.c b/fs/smb/client/smb2file.c index f35b6488d810..fb2fccbe8667 100644 --- a/fs/smb/client/smb2file.c +++ b/fs/smb/client/smb2file.c @@ -61,7 +61,10 @@ static struct smb2_symlink_err_rsp *symlink_data(const struct kvec *iov) cifs_dbg(FYI, "%s: skipping unhandled error context: 0x%x\n", __func__, le32_to_cpu(p->ErrorId)); - len = ALIGN(le32_to_cpu(p->ErrorDataLength), 8); + len = le32_to_cpu(p->ErrorDataLength); + if (len > end - ((u8 *)p + sizeof(*p))) + return ERR_PTR(-EINVAL); + len = ALIGN(len, 8); if (len > end - ((u8 *)p + sizeof(*p))) return ERR_PTR(-EINVAL);