From: Willem de Bruijn <willemb@xxxxxxxxxx>
[ Upstream commit aba36930a35e7f1fe1319b203f25c05d6c119936 ]
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 <willemb@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 d63091812342f..fbf30122e8bf2 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -940,7 +940,7 @@ 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;
@@ -957,6 +957,7 @@ alloc_new_skb:
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 eed9231c90ad5..9886a84c25117 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1357,7 +1357,7 @@ 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)
@@ -1381,6 +1381,7 @@ 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))
--
2.20.1
