Commit ec3661b4 authored by David S. Miller's avatar David S. Miller

Merge branch 'ipv6-overflow-arith'

Hannes Frederic Sowa says:

====================
overflow-arith: begin to add support for overflow builtins functions

I add a new header, linux/overflow-arith.h, as the central place to add
overflow and wrap-around checking functions. The reason I am doing so
is that it can make use of compiler supported builtin functions which
can leverage hardware.

As I need this for a fix in the ipv6 stack, which is also included in
this series, I propose to add it sooner than later over Davem's net
tree. This is also the reason why I start slowly with only the one
function I need at this time.
====================
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents c80dbe04 b72a2b01
...@@ -237,6 +237,10 @@ ...@@ -237,6 +237,10 @@
#define KASAN_ABI_VERSION 3 #define KASAN_ABI_VERSION 3
#endif #endif
#if GCC_VERSION >= 50000
#define CC_HAVE_BUILTIN_OVERFLOW
#endif
#endif /* gcc version >= 40000 specific checks */ #endif /* gcc version >= 40000 specific checks */
#if !defined(__noclone) #if !defined(__noclone)
......
#pragma once
#include <linux/kernel.h>
#ifdef CC_HAVE_BUILTIN_OVERFLOW
#define overflow_usub __builtin_usub_overflow
#else
static inline bool overflow_usub(unsigned int a, unsigned int b,
unsigned int *res)
{
*res = a - b;
return *res > a ? true : false;
}
#endif
...@@ -28,6 +28,7 @@ ...@@ -28,6 +28,7 @@
#include <linux/errno.h> #include <linux/errno.h>
#include <linux/kernel.h> #include <linux/kernel.h>
#include <linux/overflow-arith.h>
#include <linux/string.h> #include <linux/string.h>
#include <linux/socket.h> #include <linux/socket.h>
#include <linux/net.h> #include <linux/net.h>
...@@ -584,7 +585,10 @@ int ip6_fragment(struct sock *sk, struct sk_buff *skb, ...@@ -584,7 +585,10 @@ int ip6_fragment(struct sock *sk, struct sk_buff *skb,
if (np->frag_size) if (np->frag_size)
mtu = np->frag_size; mtu = np->frag_size;
} }
mtu -= hlen + sizeof(struct frag_hdr);
if (overflow_usub(mtu, hlen + sizeof(struct frag_hdr), &mtu) ||
mtu <= 7)
goto fail_toobig;
frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr, frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr,
&ipv6_hdr(skb)->saddr); &ipv6_hdr(skb)->saddr);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment