net: heap-out-of-bounds in sock_setsockopt

[Dmitry Vyukov]

Hello,

The following program triggers heap-out-of-bounds access in sock_setsockopt:

// autogenerated by syzkaller (http://github.com/google/syzkaller)
#include <syscall.h>
#include <string.h>
#include <stdint.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <linux/in.h>
#include <linux/in6.h>

#define SOF_TIMESTAMPING_OPT_ID (1<<7)

int main()
{
        int fd = socket(PF_INET6, SOCK_RAW, IPPROTO_TCP);
        struct sockaddr_in6 sa = {};
        sa.sin6_family = AF_INET6;
        sa.sin6_port = htons(13277);
        inet_pton(AF_INET6, "::1", &sa.sin6_addr);
        connect(fd, (struct sockaddr*)&sa, sizeof(sa));
        int opt = SOF_TIMESTAMPING_OPT_ID;
        setsockopt(fd, SOL_SOCKET, SO_TIMESTAMPING, &opt, sizeof(opt));
        return 0;
}


BUG: KASAN: slab-out-of-bounds in sock_setsockopt+0x1284/0x13d0 at
addr ffff88006563ec10
Read of size 4 by task syzkaller_execu/4755
=============================================================================
BUG RAWv6 (Not tainted): kasan: bad access detected
-----------------------------------------------------------------------------
INFO: Allocated in sk_prot_alloc+0x69/0x340 age=17 cpu=3 pid=4755
[<      none      >] kmem_cache_alloc+0x244/0x2c0 mm/slub.c:2607
[<      none      >] sk_prot_alloc+0x69/0x340 net/core/sock.c:1343
[<      none      >] sk_alloc+0x3a/0x6b0 net/core/sock.c:1418
[<      none      >] inet6_create+0x2c4/0xfd0 net/ipv6/af_inet6.c:170
[<      none      >] __sock_create+0x37c/0x640 net/socket.c:1162
[<     inline     >] sock_create net/socket.c:1202
[<     inline     >] SYSC_socket net/socket.c:1232
[<      none      >] SyS_socket+0xef/0x1b0 net/socket.c:1212
[<      none      >] entry_SYSCALL_64_fastpath+0x16/0x7a
arch/x86/entry/entry_64.S:185

Call Trace:
 [<ffffffff816cec2e>] __asan_report_load4_noabort+0x3e/0x40
mm/kasan/report.c:294
 [<ffffffff84affb14>] sock_setsockopt+0x1284/0x13d0 net/core/sock.c:880
 [<     inline     >] SYSC_setsockopt net/socket.c:1746
 [<ffffffff84aed7ee>] SyS_setsockopt+0x1fe/0x240 net/socket.c:1729
 [<ffffffff85c18c76>] entry_SYSCALL_64_fastpath+0x16/0x7a
arch/x86/entry/entry_64.S:185


On commit edb42dc7bc0da0125ceacab810a553ce1f0cac8d (Dec 15).
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