From: ZhangXiaoxu <zhangxiaoxu5@huawei.com>
Date: Sat, 6 Apr 2019 15:47:39 +0800
Subject: [PATCH] cifs: Fix use-after-free in SMB2_read
Git-commit: 088aaf17aa79300cab14dbee2569c58cfafd7d6e
Patch-mainline: v5.1-rc6
References: bsc#1144333, CVE-2019-15920, bsc#1149626
There is a KASAN use-after-free:
BUG: KASAN: use-after-free in SMB2_read+0x1136/0x1190
Read of size 8 at addr ffff8880b4e45e50 by task ln/1009
Should not release the 'req' because it will use in the trace.
Fixes: eccb4422cf97 ("smb3: Add ftrace tracepoints for improved SMB3 debugging")
Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
CC: Stable <stable@vger.kernel.org> 4.18+
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Acked-by: Paulo Alcantara <palcantara@suse.de>
---
fs/cifs/smb2pdu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 5d1f8d2d44e4..5d6adc63ad62 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -3448,8 +3448,6 @@ SMB2_read(const unsigned int xid, struct cifs_io_parms *io_parms,
rqst.rq_nvec = 1;
rc = cifs_send_recv(xid, ses, &rqst, &resp_buftype, flags, &rsp_iov);
- cifs_small_buf_release(req);
-
rsp = (struct smb2_read_rsp *)rsp_iov.iov_base;
if (rc) {
@@ -3471,6 +3469,8 @@ SMB2_read(const unsigned int xid, struct cifs_io_parms *io_parms,
io_parms->tcon->tid, ses->Suid,
io_parms->offset, io_parms->length);
+ cifs_small_buf_release(req);
+
*nbytes = le32_to_cpu(rsp->DataLength);
if ((*nbytes > CIFS_MAX_MSGSIZE) ||
(*nbytes > io_parms->length)) {
--
2.22.0