From aba36930a35e7f1fe1319b203f25c05d6c119936 Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Sat, 24 Nov 2018 14:21:16 -0500 Subject: net: always initialize pagedlen 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 --- net/ipv6/ip6_output.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'net/ipv6/ip6_output.c') diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 89e0d5118afe..827a3f5ff3bb 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1354,7 +1354,7 @@ emsgsize: 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) @@ -1378,6 +1378,7 @@ alloc_new_skb: 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)) -- cgit v1.2.3