From b59bde78dbf049a2671603034562940ac6eb1181 Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Thu, 15 Aug 2013 15:52:57 +0300 Subject: [PATCH] tun: signedness bug in tun_get_user() [ Upstream commit 15718ea0d844e4816dbd95d57a8a0e3e264ba90e ] The recent fix d9bf5f1309 "tun: compare with 0 instead of total_len" is not totally correct. Because "len" and "sizeof()" are size_t type, that means they are never less than zero. Signed-off-by: Dan Carpenter Acked-by: Michael S. Tsirkin Acked-by: Neil Horman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/tun.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 2491eb28a8d2..7b54f4f052d0 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1076,8 +1076,9 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, u32 rxhash; if (!(tun->flags & TUN_NO_PI)) { - if ((len -= sizeof(pi)) > total_len) + if (len < sizeof(pi)) return -EINVAL; + len -= sizeof(pi); if (memcpy_fromiovecend((void *)&pi, iv, 0, sizeof(pi))) return -EFAULT; @@ -1085,8 +1086,9 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, } if (tun->flags & TUN_VNET_HDR) { - if ((len -= tun->vnet_hdr_sz) > total_len) + if (len < tun->vnet_hdr_sz) return -EINVAL; + len -= tun->vnet_hdr_sz; if (memcpy_fromiovecend((void *)&gso, iv, offset, sizeof(gso))) return -EFAULT; -- 2.39.5