syzbot


KASAN: use-after-free Read in ip_icmp_error

Status: fixed on 2020/07/17 17:58
Subsystems: net
[Documentation on labels]
Fix commit: 239174945dac tcp: tcp_v4_err() icmp skb is named icmp_skb
First crash: 1283d, last: 1282d
Cause bisection: introduced by (bisect log) :
commit 45af29ca761c275e350cca659856bc56f1035ef9
Author: Eric Dumazet <edumazet@google.com>
Date: Sun May 24 18:00:02 2020 +0000

  tcp: allow traceroute -Mtcp for unpriv users

Crash: general protection fault in skb_clone (log)
Repro: C syz .config
  

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in ip_icmp_error+0x52a/0x5a0 net/ipv4/ip_sockglue.c:404
Read of size 1 at addr ffff8880a219afff by task swapper/0/0

CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.7.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x413 mm/kasan/report.c:382
 __kasan_report.cold+0x20/0x38 mm/kasan/report.c:511
 kasan_report+0x33/0x50 mm/kasan/common.c:625
 ip_icmp_error+0x52a/0x5a0 net/ipv4/ip_sockglue.c:404
 tcp_v4_err+0x9b2/0x1d00 net/ipv4/tcp_ipv4.c:576
 icmp_socket_deliver+0x1e4/0x360 net/ipv4/icmp.c:803
 icmp_unreach+0x33b/0xab0 net/ipv4/icmp.c:920
 icmp_rcv+0xee6/0x15f0 net/ipv4/icmp.c:1102
 ip_protocol_deliver_rcu+0x57/0x880 net/ipv4/ip_input.c:204
 ip_local_deliver_finish+0x220/0x360 net/ipv4/ip_input.c:231
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ip_local_deliver+0x1c8/0x4e0 net/ipv4/ip_input.c:252
 dst_input include/net/dst.h:441 [inline]
 ip_rcv_finish+0x1da/0x2f0 net/ipv4/ip_input.c:428
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ip_rcv+0xd0/0x3c0 net/ipv4/ip_input.c:539
 __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5268
 __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5382
 process_backlog+0x21e/0x7a0 net/core/dev.c:6214
 napi_poll net/core/dev.c:6659 [inline]
 net_rx_action+0x4c2/0x1070 net/core/dev.c:6727
 __do_softirq+0x26c/0x9f7 kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x192/0x1d0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:546 [inline]
 smp_apic_timer_interrupt+0x19e/0x600 arch/x86/kernel/apic/apic.c:1140
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61
Code: cc cc cc cc cc cc cc cc cc cc cc cc e9 07 00 00 00 0f 00 2d d4 c3 52 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d c4 c3 52 00 fb f4 <c3> cc 41 56 41 55 41 54 55 53 e8 93 4c 8b f9 e8 ce 81 c4 fb 0f 1f
RSP: 0018:ffffffff89807d98 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff132980f RBX: ffffffff89886540 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffffffff89886e04
RBP: dffffc0000000000 R08: ffffffff89886540 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: fffffbfff1310ca8
R13: 0000000000000000 R14: ffffffff8a8a4bc0 R15: 0000000000000000
 arch_safe_halt arch/x86/include/asm/paravirt.h:144 [inline]
 default_idle+0x49/0x350 arch/x86/kernel/process.c:697
 cpuidle_idle_call kernel/sched/idle.c:154 [inline]
 do_idle+0x393/0x690 kernel/sched/idle.c:269
 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:361
 start_kernel+0x97d/0x9ba init/main.c:1040
 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

Allocated by task 1:
 save_stack+0x1b/0x40 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc mm/kasan/common.c:495 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:468
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x161/0x7a0 mm/slab.c:3665
 kmalloc include/linux/slab.h:560 [inline]
 tomoyo_realpath_from_path+0xc2/0x620 security/tomoyo/realpath.c:252
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x214/0x400 security/tomoyo/file.c:822
 security_inode_getattr+0xeb/0x150 security/security.c:1273
 vfs_getattr+0x22/0x60 fs/stat.c:117
 vfs_statx+0x142/0x1e0 fs/stat.c:201
 vfs_lstat include/linux/fs.h:3284 [inline]
 __do_sys_newlstat+0x96/0x120 fs/stat.c:364
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 1:
 save_stack+0x1b/0x40 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 kasan_set_free_info mm/kasan/common.c:317 [inline]
 __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:456
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x109/0x2b0 mm/slab.c:3757
 tomoyo_realpath_from_path+0x18f/0x620 security/tomoyo/realpath.c:289
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x214/0x400 security/tomoyo/file.c:822
 security_inode_getattr+0xeb/0x150 security/security.c:1273
 vfs_getattr+0x22/0x60 fs/stat.c:117
 vfs_statx+0x142/0x1e0 fs/stat.c:201
 vfs_lstat include/linux/fs.h:3284 [inline]
 __do_sys_newlstat+0x96/0x120 fs/stat.c:364
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

The buggy address belongs to the object at ffff8880a219a000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 4095 bytes inside of
 4096-byte region [ffff8880a219a000, ffff8880a219b000)
The buggy address belongs to the page:
page:ffffea0002886680 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea0002886680 order:1 compound_mapcount:0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea00027a6a88 ffffea0002292a88 ffff8880aa002000
raw: 0000000000000000 ffff8880a219a000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a219ae80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a219af00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880a219af80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                                ^
 ffff8880a219b000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a219b080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (14):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/05/26 22:47 net-next-old d52caf0404e6 9072c126 .config console log report syz C ci-upstream-net-kasan-gce
2020/05/26 22:22 net-next-old d52caf0404e6 9072c126 .config console log report syz C ci-upstream-net-kasan-gce
2020/05/26 21:57 net-next-old d52caf0404e6 9072c126 .config console log report syz C ci-upstream-net-kasan-gce
2020/05/26 20:55 net-next-old d52caf0404e6 9072c126 .config console log report syz C ci-upstream-net-kasan-gce
2020/05/26 14:52 net-next-old d52caf0404e6 8ca3b7d2 .config console log report syz C ci-upstream-net-kasan-gce
2020/05/26 14:18 net-next-old d52caf0404e6 8ca3b7d2 .config console log report syz C ci-upstream-net-kasan-gce
2020/05/27 05:41 linux-next b0523c7b1c9d 9072c126 .config console log report syz C ci-upstream-linux-next-kasan-gce-root
2020/05/27 03:09 linux-next b0523c7b1c9d 9072c126 .config console log report syz C ci-upstream-linux-next-kasan-gce-root
2020/05/27 02:06 linux-next b0523c7b1c9d 9072c126 .config console log report syz C ci-upstream-linux-next-kasan-gce-root
2020/05/27 00:57 linux-next b0523c7b1c9d 9072c126 .config console log report syz C ci-upstream-linux-next-kasan-gce-root
2020/05/26 16:24 linux-next b0523c7b1c9d 8ca3b7d2 .config console log report syz C ci-upstream-linux-next-kasan-gce-root
2020/05/26 16:06 linux-next b0523c7b1c9d 8ca3b7d2 .config console log report syz C ci-upstream-linux-next-kasan-gce-root
2020/05/26 13:14 net-next-old d52caf0404e6 8ca3b7d2 .config console log report ci-upstream-net-kasan-gce
2020/05/26 11:33 net-next-old d52caf0404e6 8ca3b7d2 .config console log report ci-upstream-net-kasan-gce
* Struck through repros no longer work on HEAD.