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BUG: KASAN: user-memory-access in atomic_read include/asm-generic/atomic-instrumented.h:26 [inline]
BUG: KASAN: user-memory-access in atomic_fetch_add_unless include/linux/atomic-fallback.h:1086 [inline]
BUG: KASAN: user-memory-access in atomic_add_unless include/linux/atomic-fallback.h:1111 [inline]
BUG: KASAN: user-memory-access in atomic_inc_not_zero include/linux/atomic-fallback.h:1127 [inline]
BUG: KASAN: user-memory-access in dst_hold_safe include/net/dst.h:297 [inline]
BUG: KASAN: user-memory-access in ip6_hold_safe+0xad/0x380 net/ipv6/route.c:1010
Read of size 4 at addr 0000000000008230 by task syz-executor.0/9421

CPU: 0 PID: 9421 Comm: syz-executor.0 Not tainted 5.1.0-rc2+ #117
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 kasan_report.cold+0x5/0x40 mm/kasan/report.c:321
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x123/0x190 mm/kasan/generic.c:191
 kasan_check_read+0x11/0x20 mm/kasan/common.c:102
 atomic_read include/asm-generic/atomic-instrumented.h:26 [inline]
 atomic_fetch_add_unless include/linux/atomic-fallback.h:1086 [inline]
 atomic_add_unless include/linux/atomic-fallback.h:1111 [inline]
 atomic_inc_not_zero include/linux/atomic-fallback.h:1127 [inline]
 dst_hold_safe include/net/dst.h:297 [inline]
 ip6_hold_safe+0xad/0x380 net/ipv6/route.c:1010
 rt6_get_pcpu_route net/ipv6/route.c:1232 [inline]
 ip6_pol_route+0x346/0x1080 net/ipv6/route.c:1893
 ip6_pol_route_output+0x54/0x70 net/ipv6/route.c:2069
 fib6_rule_lookup+0x128/0x560 net/ipv6/fib6_rules.c:118
 ip6_route_output_flags+0x2c4/0x350 net/ipv6/route.c:2098
 ip6_route_output include/net/ip6_route.h:88 [inline]
 ip6_dst_lookup_tail+0xd10/0x1b30 net/ipv6/ip6_output.c:964
 ip6_dst_lookup_flow+0xa8/0x220 net/ipv6/ip6_output.c:1092
 l2tp_ip6_sendmsg+0xa26/0x1790 net/l2tp/l2tp_ip6.c:622
 inet_sendmsg+0x147/0x5e0 net/ipv4/af_inet.c:802
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg+0xdd/0x130 net/socket.c:661
 ___sys_sendmsg+0x3e2/0x930 net/socket.c:2260
 __sys_sendmmsg+0x1bf/0x4d0 net/socket.c:2355
 __do_sys_sendmmsg net/socket.c:2384 [inline]
 __se_sys_sendmmsg net/socket.c:2381 [inline]
 __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2381
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458209
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f1c40fa5c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000458209
RDX: 0000000000000008 RSI: 0000000020000080 RDI: 0000000000000003
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1c40fa66d4
R13: 00000000004c5190 R14: 00000000004d92e0 R15: 00000000ffffffff
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