================================================================== BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] BUG: KASAN: use-after-free in atomic_fetch_add_unless include/linux/atomic.h:575 [inline] BUG: KASAN: use-after-free in atomic_add_unless include/linux/atomic.h:597 [inline] BUG: KASAN: use-after-free in dst_hold_safe include/net/dst.h:308 [inline] BUG: KASAN: use-after-free in ip6_hold_safe+0xa7/0x3a0 net/ipv6/route.c:1023 Read of size 4 at addr ffff8880944da8fc by task syz-executor.3/30961 CPU: 0 PID: 30961 Comm: syz-executor.3 Not tainted 5.0.0-rc6+ #75 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 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 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:100 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] atomic_fetch_add_unless include/linux/atomic.h:575 [inline] atomic_add_unless include/linux/atomic.h:597 [inline] dst_hold_safe include/net/dst.h:308 [inline] ip6_hold_safe+0xa7/0x3a0 net/ipv6/route.c:1023 rt6_get_pcpu_route net/ipv6/route.c:1243 [inline] ip6_pol_route+0x33d/0xf00 net/ipv6/route.c:1892 ip6_pol_route_input+0x65/0x80 net/ipv6/route.c:1911 fib6_rule_lookup+0x128/0x560 net/ipv6/fib6_rules.c:118 ip6_route_input_lookup+0xb7/0xd0 net/ipv6/route.c:1923 ip6_route_input+0x5e6/0x9e0 net/ipv6/route.c:2058 ip6_rcv_finish_core.isra.0+0x174/0x590 net/ipv6/ip6_input.c:63 ip6_rcv_finish+0x17d/0x320 net/ipv6/ip6_input.c:74 NF_HOOK include/linux/netfilter.h:289 [inline] NF_HOOK include/linux/netfilter.h:283 [inline] ipv6_rcv+0x10e/0x420 net/ipv6/ip6_input.c:272 __netif_receive_skb_one_core+0x115/0x1a0 net/core/dev.c:4973 __netif_receive_skb+0x2c/0x1c0 net/core/dev.c:5083 netif_receive_skb_internal+0x117/0x660 net/core/dev.c:5186 netif_receive_skb+0x6e/0x5a0 net/core/dev.c:5261 tun_rx_batched.isra.0+0x4f7/0x840 drivers/net/tun.c:1562 tun_get_user+0x2588/0x38d0 drivers/net/tun.c:1991 tun_chr_write_iter+0xbd/0x160 drivers/net/tun.c:2019 call_write_iter include/linux/fs.h:1863 [inline] do_iter_readv_writev+0x5e0/0x8e0 fs/read_write.c:680 do_iter_write fs/read_write.c:956 [inline] do_iter_write+0x184/0x610 fs/read_write.c:937 compat_writev+0x1f6/0x3a0 fs/read_write.c:1270 do_compat_writev+0xf5/0x1f0 fs/read_write.c:1291 __do_compat_sys_writev fs/read_write.c:1302 [inline] __se_compat_sys_writev fs/read_write.c:1298 [inline] __ia32_compat_sys_writev+0x74/0xb0 fs/read_write.c:1298 do_syscall_32_irqs_on arch/x86/entry/common.c:326 [inline] do_fast_syscall_32+0x281/0xc98 arch/x86/entry/common.c:397 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 RIP: 0023:0xf7ffd869 Code: 85 d2 74 02 89 0a 5b 5d c3 8b 04 24 c3 8b 14 24 c3 8b 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90 RSP: 002b:00000000f5df9054 EFLAGS: 00000292 ORIG_RAX: 0000000000000092 RAX: ffffffffffffffda RBX: 00000000000000f0 RCX: 00000000f5df90a4 RDX: 0000000000000001 RSI: 0000000020000100 RDI: 00000000ffffffff RBP: 00000000f5df9168 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 3456: save_stack+0x45/0xd0 mm/kasan/common.c:73 set_track mm/kasan/common.c:85 [inline] __kasan_kmalloc mm/kasan/common.c:496 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:469 kasan_kmalloc mm/kasan/common.c:504 [inline] kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:411 kmem_cache_alloc+0x12d/0x710 mm/slab.c:3543 dup_mm kernel/fork.c:1311 [inline] copy_mm kernel/fork.c:1375 [inline] copy_process.part.0+0x2afe/0x79a0 kernel/fork.c:1917 copy_process kernel/fork.c:1710 [inline] _do_fork+0x257/0xfe0 kernel/fork.c:2227 __do_compat_sys_x86_clone arch/x86/ia32/sys_ia32.c:240 [inline] __se_compat_sys_x86_clone arch/x86/ia32/sys_ia32.c:236 [inline] __ia32_compat_sys_x86_clone+0xbc/0x140 arch/x86/ia32/sys_ia32.c:236 do_syscall_32_irqs_on arch/x86/entry/common.c:326 [inline] do_fast_syscall_32+0x281/0xc98 arch/x86/entry/common.c:397 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 Freed by task 29926: save_stack+0x45/0xd0 mm/kasan/common.c:73 set_track mm/kasan/common.c:85 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:458 kasan_slab_free+0xe/0x10 mm/kasan/common.c:466 __cache_free mm/slab.c:3487 [inline] kmem_cache_free+0x86/0x260 mm/slab.c:3749 __mmdrop+0x238/0x320 kernel/fork.c:678 mmdrop include/linux/sched/mm.h:49 [inline] __mmput kernel/fork.c:1057 [inline] mmput+0x3d6/0x4c0 kernel/fork.c:1068 exit_mm kernel/exit.c:545 [inline] do_exit+0x838/0x2fd0 kernel/exit.c:862 do_group_exit+0x135/0x370 kernel/exit.c:979 get_signal+0x399/0x1d50 kernel/signal.c:2575 do_signal+0x87/0x1940 arch/x86/kernel/signal.c:816 exit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_32_irqs_on arch/x86/entry/common.c:341 [inline] do_fast_syscall_32+0xa9d/0xc98 arch/x86/entry/common.c:397 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 The buggy address belongs to the object at ffff8880944da340 which belongs to the cache mm_struct(65:syz3) of size 1496 The buggy address is located 1468 bytes inside of 1496-byte region [ffff8880944da340, ffff8880944da918) The buggy address belongs to the page: page:ffffea0002513680 count:1 mapcount:0 mapping:ffff8880a1a64900 index:0xffff8880944db040 compound_mapcount: 0 flags: 0x1fffc0000010200(slab|head) raw: 01fffc0000010200 ffffea00025c0988 ffffea000233c688 ffff8880a1a64900 raw: ffff8880944db040 ffff8880944da340 0000000100000003 ffff88806e086a00 page dumped because: kasan: bad access detected page->mem_cgroup:ffff88806e086a00 Memory state around the buggy address: ffff8880944da780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880944da800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880944da880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880944da900: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880944da980: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00 ==================================================================