From bcb1dc73b6f8b831c18d750a2e0f5909bc79abba Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Thu, 14 Feb 2019 10:18:04 +0800 Subject: [PATCH] net: always initialize pagedlen mainline inclusion from mainline-4.20 commit aba36930a35e category: bugfix bugzilla: 6118 CVE: NA ------------------------------------------------- In ip packet generation, pagedlen is initialized for each skb at the start of the loop in __ip(6)_append_data, before label alloc_new_skb. Depending on compiler options, code can be generated that jumps to this label, triggering use of an an uninitialized variable. In practice, at -O2, the generated code moves the initialization below the label. But the code should not rely on that for correctness. Fixes: 15e36f5b8e98 ("udp: paged allocation with gso") Signed-off-by: Willem de Bruijn Signed-off-by: David S. Miller Signed-off-by: Keefe LIU Reviewed-by: Wei Yongjun Signed-off-by: Yang Yingliang --- net/ipv4/ip_output.c | 3 ++- net/ipv6/ip6_output.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 9c4e72e9c60a..ac439172a5e2 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -939,7 +939,7 @@ static int __ip_append_data(struct sock *sk, unsigned int fraglen; unsigned int fraggap; unsigned int alloclen; - unsigned int pagedlen = 0; + unsigned int pagedlen; struct sk_buff *skb_prev; alloc_new_skb: skb_prev = skb; @@ -956,6 +956,7 @@ static int __ip_append_data(struct sock *sk, if (datalen > mtu - fragheaderlen) datalen = maxfraglen - fragheaderlen; fraglen = datalen + fragheaderlen; + pagedlen = 0; if ((flags & MSG_MORE) && !(rt->dst.dev->features&NETIF_F_SG)) diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 0bb87f3a10c7..98334d795d8a 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1355,7 +1355,7 @@ static int __ip6_append_data(struct sock *sk, unsigned int fraglen; unsigned int fraggap; unsigned int alloclen; - unsigned int pagedlen = 0; + unsigned int pagedlen; alloc_new_skb: /* There's no room in the current skb */ if (skb) @@ -1379,6 +1379,7 @@ static int __ip6_append_data(struct sock *sk, if (datalen > (cork->length <= mtu && !(cork->flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - fragheaderlen) datalen = maxfraglen - fragheaderlen - rt->dst.trailer_len; fraglen = datalen + fragheaderlen; + pagedlen = 0; if ((flags & MSG_MORE) && !(rt->dst.dev->features&NETIF_F_SG)) -- GitLab