Commit 5fe7f7b7 authored by Namjae Jeon's avatar Namjae Jeon Committed by Steve French
Browse files

ksmbd: fix out-of-bound read in smb2_write 



ksmbd_smb2_check_message doesn't validate hdr->NextCommand. If
->NextCommand is bigger than Offset + Length of smb2 write, It will
allow oversized smb2 write length. It will cause OOB read in smb2_write.

Cc: stable@vger.kernel.org
Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-21164
Signed-off-by: default avatarNamjae Jeon <linkinjeon@kernel.org>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 40b268d3

fs/smb/server/smb2misc.c

+9 −3
Original line number Diff line number Diff line
@@ -351,10 +351,16 @@ int ksmbd_smb2_check_message(struct ksmbd_work *work) 
	int command;

	__u32 clc_len;  /* calculated length */

	__u32 len = get_rfc1002_len(work->request_buf);

	__u32 req_struct_size;

	__u32 req_struct_size, next_cmd = le32_to_cpu(hdr->NextCommand);



	if (le32_to_cpu(hdr->NextCommand) > 0)

		len = le32_to_cpu(hdr->NextCommand);

	if ((u64)work->next_smb2_rcv_hdr_off + next_cmd > len) {

		pr_err("next command(%u) offset exceeds smb msg size\n",

				next_cmd);

		return 1;

	}



	if (next_cmd > 0)

		len = next_cmd;

	else if (work->next_smb2_rcv_hdr_off)

		len -= work->next_smb2_rcv_hdr_off;