From c69330a855ab4342d304f67f8c1e7d1fa2686bec Mon Sep 17 00:00:00 2001 From: ZhangXiaoxu Date: Sat, 6 Apr 2019 15:47:39 +0800 Subject: [PATCH] cifs: Fix use-after-free in SMB2_read commit 088aaf17aa79300cab14dbee2569c58cfafd7d6e upstream. 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 Signed-off-by: Steve French CC: Stable 4.18+ Reviewed-by: Pavel Shilovsky Signed-off-by: Greg Kroah-Hartman --- 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 299d8e4..c6fd3ac 100644 --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -3273,8 +3273,6 @@ 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) { @@ -3293,6 +3291,8 @@ 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