From: Alexander Potapenko <glider@google.com>
Date: Fri, 18 May 2018 14:23:18 +0000 (+0200)
Subject: scsi: sg: allocate with __GFP_ZERO in sg_build_indirect()
X-Git-Tag: v4.4.133~8
X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=93314640426ddb6af618d0802e622f6fa771792c;p=linux

scsi: sg: allocate with __GFP_ZERO in sg_build_indirect()

commit a45b599ad808c3c982fdcdc12b0b8611c2f92824 upstream.

This shall help avoid copying uninitialized memory to the userspace when
calling ioctl(fd, SG_IO) with an empty command.

Reported-by: syzbot+7d26fc1eea198488deab@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index cb19c9ad1b57..841f3fbec77c 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1903,7 +1903,7 @@ retry:
 		num = (rem_sz > scatter_elem_sz_prev) ?
 			scatter_elem_sz_prev : rem_sz;
 
-		schp->pages[k] = alloc_pages(gfp_mask, order);
+		schp->pages[k] = alloc_pages(gfp_mask | __GFP_ZERO, order);
 		if (!schp->pages[k])
 			goto out;