Revert "Merge branch 'ipv6-overflow-arith'"

strssndktn · davem330 · commit 1e0d69a9cc91 · 2015-10-29T07:01:48.000-07:00
Linus dislikes these changes. To not hold up the net-merge let's revert it for now and fix the bug like Linus suggested. This reverts commit ec3661b, reversing changes made to c80dbe0. Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
@@ -237,10 +237,6 @@
 #define KASAN_ABI_VERSION 3
 #endif
 
-#if GCC_VERSION >= 50000
-#define CC_HAVE_BUILTIN_OVERFLOW
-#endif
-
 #endif	/* gcc version >= 40000 specific checks */
 
 #if !defined(__noclone)
diff --git a/include/linux/overflow-arith.h b/include/linux/overflow-arith.h
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
@@ -28,7 +28,6 @@
 
 #include <linux/errno.h>
 #include <linux/kernel.h>
-#include <linux/overflow-arith.h>
 #include <linux/string.h>
 #include <linux/socket.h>
 #include <linux/net.h>
@@ -585,10 +584,7 @@ int ip6_fragment(struct sock *sk, struct sk_buff *skb,
 		if (np->frag_size)
 			mtu = np->frag_size;
 	}
-
-	if (overflow_usub(mtu, hlen + sizeof(struct frag_hdr), &mtu) ||
-	    mtu <= 7)
-		goto fail_toobig;
+	mtu -= hlen + sizeof(struct frag_hdr);
 
 	frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr,
 				    &ipv6_hdr(skb)->saddr);
