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: David S. Miller <davem@davemloft.net>
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commit
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@ -237,6 +237,10 @@
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#define KASAN_ABI_VERSION 3
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#define KASAN_ABI_VERSION 3
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#endif
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#endif
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#if GCC_VERSION >= 50000
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#define CC_HAVE_BUILTIN_OVERFLOW
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#endif
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#endif /* gcc version >= 40000 specific checks */
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#endif /* gcc version >= 40000 specific checks */
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#if !defined(__noclone)
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#if !defined(__noclone)
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18
include/linux/overflow-arith.h
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18
include/linux/overflow-arith.h
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@ -0,0 +1,18 @@
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#pragma once
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#include <linux/kernel.h>
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#ifdef CC_HAVE_BUILTIN_OVERFLOW
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#define overflow_usub __builtin_usub_overflow
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#else
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static inline bool overflow_usub(unsigned int a, unsigned int b,
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unsigned int *res)
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{
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*res = a - b;
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return *res > a ? true : false;
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}
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#endif
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@ -28,6 +28,7 @@
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#include <linux/errno.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/kernel.h>
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#include <linux/overflow-arith.h>
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#include <linux/string.h>
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#include <linux/string.h>
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#include <linux/socket.h>
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#include <linux/socket.h>
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#include <linux/net.h>
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#include <linux/net.h>
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@ -584,7 +585,10 @@ int ip6_fragment(struct sock *sk, struct sk_buff *skb,
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if (np->frag_size)
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if (np->frag_size)
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mtu = np->frag_size;
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mtu = np->frag_size;
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}
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}
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mtu -= hlen + sizeof(struct frag_hdr);
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if (overflow_usub(mtu, hlen + sizeof(struct frag_hdr), &mtu) ||
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mtu <= 7)
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goto fail_toobig;
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frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr,
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frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr,
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&ipv6_hdr(skb)->saddr);
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&ipv6_hdr(skb)->saddr);
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