From 4d0dd4350a4107265fd8701d4b26fdc033ad28cc Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sat, 21 Mar 2015 20:08:18 -0400
Subject: [PATCH] sg_start_req(): make sure that there's not too many elements
in iovec
commit 451a2886b6bf90e2fb378f7c46c655450fb96e81 upstream.
unfortunately, allowing an arbitrary 16bit value means a possibility of
overflow in the calculation of total number of pages in bio_map_user_iov() -
we rely on there being no more than PAGE_SIZE members of sum in the
first loop there. If that sum wraps around, we end up allocating
too small array of pointers to pages and it's easy to overflow it in
the second loop.
X-Coverup: TINC (and there's no lumber cartel either)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[bwh: s/MAX_UIOVEC/UIO_MAXIOV/. This was fixed upstream by commit
fdc81f45e9f5 ("sg_start_req(): use import_iovec()"), but we don't have
that function.]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/scsi/sg.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index eb81c98386b9..721d839d6c54 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1694,6 +1694,9 @@ static int sg_start_req(Sg_request *srp, unsigned char *cmd)
md->from_user = 0;
}
+ if (unlikely(iov_count > UIO_MAXIOV))
+ return -EINVAL;
+
if (iov_count) {
int len, size = sizeof(struct sg_iovec) * iov_count;
struct iovec *iov;
--
GitLab