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KASAN: slab-out-of-bounds Read in skb_release_data

Status: fixed on 2017/10/24 06:54
Fix commit: 0bbd7dad34f8 tun: make tun_build_skb() thread safe
First crash: 2437d, last: 2437d

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in skb_release_data+0x5cf/0x790 net/core/skbuff.c:567
Read of size 1 at addr ffff880036948442 by task swapper/2/0

CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.13.0-rc5-next-20170816+ #4
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x24e/0x340 mm/kasan/report.c:409
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:427
 skb_release_data+0x5cf/0x790 net/core/skbuff.c:567
 skb_release_all+0x4a/0x60 net/core/skbuff.c:631
 __kfree_skb net/core/skbuff.c:645 [inline]
 kfree_skb+0x15d/0x4c0 net/core/skbuff.c:663
 inet_frag_destroy+0x121/0x270 net/ipv4/inet_fragment.c:304
 inet_frag_put include/net/inet_frag.h:133 [inline]
 ipq_put net/ipv4/ip_fragment.c:170 [inline]
 ip_expire+0x1be/0x6d0 net/ipv4/ip_fragment.c:254
 call_timer_fn+0x233/0x830 kernel/time/timer.c:1268
 expire_timers kernel/time/timer.c:1307 [inline]
 __run_timers+0x7fd/0xb90 kernel/time/timer.c:1601
 run_timer_softirq+0x21/0x80 kernel/time/timer.c:1614
 __do_softirq+0x2f5/0xba3 kernel/softirq.c:284
 invoke_softirq kernel/softirq.c:364 [inline]
 irq_exit+0x1cc/0x200 kernel/softirq.c:405
 exiting_irq arch/x86/include/asm/apic.h:638 [inline]
 smp_trace_apic_timer_interrupt+0x139/0x6a0 arch/x86/kernel/apic/apic.c:1065
 trace_apic_timer_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:577
 </IRQ>
RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:53
RSP: 0018:ffff88006dab7db0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff10
RAX: dffffc0000000000 RBX: 1ffff1000db56fb9 RCX: 0100000000000000
RDX: 1ffffffff0b58d6c RSI: 0000000000000000 RDI: ffffffff85ac6b60
RBP: ffff88006dab7db0 R08: ffffffff857f0a90 R09: 1ffff1000db56f4f
R10: ffff88007fff7090 R11: ffff88007fff709d R12: ffffffff85ac6b50
R13: ffff88006dab7e68 R14: 0000000000000000 R15: ffff88006daac040
 arch_safe_halt arch/x86/include/asm/paravirt.h:98 [inline]
 default_idle+0xbf/0x460 arch/x86/kernel/process.c:341
 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:332
 default_idle_call+0x36/0x90 kernel/sched/idle.c:98
 cpuidle_idle_call kernel/sched/idle.c:156 [inline]
 do_idle+0x256/0x3b0 kernel/sched/idle.c:246
 cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:351
 start_secondary+0x277/0x310 arch/x86/kernel/smpboot.c:275
 secondary_startup_64+0xa5/0xa5 arch/x86/kernel/head_64.S:235

Allocated by task 20100:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3561
 getname_flags+0xcb/0x580 fs/namei.c:137
 getname+0x19/0x20 fs/namei.c:208
 do_sys_open+0x2e7/0x6d0 fs/open.c:1053
 SYSC_open fs/open.c:1077 [inline]
 SyS_open+0x2d/0x40 fs/open.c:1072
 entry_SYSCALL_64_fastpath+0x1f/0xbe

Freed by task 20100:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3503 [inline]
 kmem_cache_free+0x77/0x280 mm/slab.c:3763
 putname+0xee/0x130 fs/namei.c:257
 do_sys_open+0x31b/0x6d0 fs/open.c:1068
 SYSC_open fs/open.c:1077 [inline]
 SyS_open+0x2d/0x40 fs/open.c:1072
 entry_SYSCALL_64_fastpath+0x1f/0xbe

The buggy address belongs to the object at ffff880036948940
 which belongs to the cache names_cache of size 4096
The buggy address is located 1278 bytes to the left of
 4096-byte region [ffff880036948940, ffff880036949940)
The buggy address belongs to the page:
page:ffffea0000da5200 count:1 mapcount:0 mapping:ffff880036948940 index:0x0 compound_mapcount: 0
flags: 0x100000000008100(slab|head)
raw: 0100000000008100 ffff880036948940 0000000000000000 0000000100000001
raw: ffffea00009a14a0 ffffea0000eb2020 ffff88003e87c200 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff880036948300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff880036948380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff880036948400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                           ^
 ffff880036948480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff880036948500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2017/08/16 19:45 linux-next 5d51332f20b2 f93be584 .config console log report skylake-linux-next-kasan-qemu
* Struck through repros no longer work on HEAD.