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

Message ID 1554536859-139778-3-git-send-email-zhangxiaoxu5@huawei.com (mailing list archive)
State New, archived
Headers show
Series Fix KASAN use-after free in SMB2_write and SMB2_read | expand

Commit Message

Zhang Xiaoxu April 6, 2019, 7:47 a.m. UTC 
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(-)
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Patch

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)) {