In the Linux kernel, the following vulnerability has been resolved: ipv6: Fix signed integer overflow in __ip6_append_data Resurrect ubsan overflow checks and ubsan report this warning, fix it by change the variable [length] type to size_t. UBSAN: signed-integer-overflow in net/ipv6/ip6_output.c:1489:19 2147479552 + 8567 cannot be represented in type 'int' CPU: 0 PID: 253 Comm: err Not tainted 5.16.0+ #1 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x214/0x230 show_stack+0x30/0x78 dump_stack_lvl+0xf8/0x118 dump_stack+0x18/0x30 ubsan_epilogue+0x18/0x60 handle_overflow+0xd0/0xf0 __ubsan_handle_add_overflow+0x34/0x44 __ip6_append_data.isra.48+0x1598/0x1688 ip6_append_data+0x128/0x260 udpv6_sendmsg+0x680/0xdd0 inet6_sendmsg+0x54/0x90 sock_sendmsg+0x70/0x88 ____sys_sendmsg+0xe8/0x368 ___sys_sendmsg+0x98/0xe0 __sys_sendmmsg+0xf4/0x3b8 __arm64_sys_sendmmsg+0x34/0x48 invoke_syscall+0x64/0x160 el0_svc_common.constprop.4+0x124/0x300 do_el0_svc+0x44/0xc8 el0_svc+0x3c/0x1e8 el0t_64_sync_handler+0x88/0xb0 el0t_64_sync+0x16c/0x170 Changes since v1: -Change the variable [length] type to unsigned, as Eric Dumazet suggested. Changes since v2: -Don't change exthdrlen type in ip6_make_skb, as Paolo Abeni suggested. Changes since v3: -Don't change ulen type in udpv6_sendmsg and l2tp_ip6_sendmsg, as Jakub Kicinski suggested.
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.