[PATCH v2 0/2] Fix KASAN use-after free in SMB2_write and SMB2_read

[PATCH v2 0/2] Fix KASAN use-after free in SMB2_write and SMB2_read

[ZhangXiaoxu]

v1->v2: Add Fixes: eccb4422cf97(smb3: Add ftrace tracepoints for improved SMB3 debugging)

The trace function use the 'req' after released.

ZhangXiaoxu (2):
  cifs: Fix use-after-free in SMB2_write
  cifs: Fix use-after-free in SMB2_read

 fs/cifs/smb2pdu.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

-- 
2.7.4

[PATCH v2 1/2] cifs: Fix use-after-free in SMB2_write

[ZhangXiaoxu]

There is a KASAN use-after-free:
BUG: KASAN: use-after-free in SMB2_write+0x1342/0x1580
Read of size 8 at addr ffff8880b6a8e450 by task ln/4196

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>
---
 fs/cifs/smb2pdu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 21ac19f..6cf4e88 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -3752,7 +3752,6 @@ SMB2_write(const unsigned int xid, struct cifs_io_parms *io_parms,
 
 	rc = cifs_send_recv(xid, io_parms->tcon->ses, &rqst,
 			    &resp_buftype, flags, &rsp_iov);
-	cifs_small_buf_release(req);
 	rsp = (struct smb2_write_rsp *)rsp_iov.iov_base;
 
 	if (rc) {
@@ -3770,6 +3769,7 @@ SMB2_write(const unsigned int xid, struct cifs_io_parms *io_parms,
 				     io_parms->offset, *nbytes);
 	}
 
+	cifs_small_buf_release(req);
 	free_rsp_buf(resp_buftype, rsp);
 	return rc;
 }
-- 
2.7.4

[PATCH v2 2/2] cifs: Fix use-after-free in SMB2_read

[ZhangXiaoxu]

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>
---
 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 6cf4e88..5f011a8 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -3431,8 +3431,6 @@ 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) {
@@ -3454,6 +3452,8 @@ 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)) {
-- 
2.7.4

Re: [PATCH v2 1/2] cifs: Fix use-after-free in SMB2_write

[Steve French]

Presumably cc: stable v4.18+

On Sat, Apr 6, 2019 at 2:45 AM ZhangXiaoxu <zhangxiaoxu5@huawei.com> wrote:
>
> There is a KASAN use-after-free:
> BUG: KASAN: use-after-free in SMB2_write+0x1342/0x1580
> Read of size 8 at addr ffff8880b6a8e450 by task ln/4196
>
> 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>
> ---
>  fs/cifs/smb2pdu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
> index 21ac19f..6cf4e88 100644
> --- a/fs/cifs/smb2pdu.c
> +++ b/fs/cifs/smb2pdu.c
> @@ -3752,7 +3752,6 @@ SMB2_write(const unsigned int xid, struct cifs_io_parms *io_parms,
>
>         rc = cifs_send_recv(xid, io_parms->tcon->ses, &rqst,
>                             &resp_buftype, flags, &rsp_iov);
> -       cifs_small_buf_release(req);
>         rsp = (struct smb2_write_rsp *)rsp_iov.iov_base;
>
>         if (rc) {
> @@ -3770,6 +3769,7 @@ SMB2_write(const unsigned int xid, struct cifs_io_parms *io_parms,
>                                      io_parms->offset, *nbytes);
>         }
>
> +       cifs_small_buf_release(req);
>         free_rsp_buf(resp_buftype, rsp);
>         return rc;
>  }
> --
> 2.7.4
>


-- 
Thanks,

Steve