KASAN: use-after-free Read in erspan_xmit
From: syzbot <hidden>
Date: 2018-01-22 19:59:43
Hello, syzbot hit the following crash on net-next commit 9d6474e458b13a94a0d5b141f2b8f38adf1991ae (Mon Jan 22 02:55:38 2018 +0000) tun: add missing rcu annotation So far this crash happened 9 times on net-next. C reproducer is attached. syzkaller reproducer is attached. Raw console output is attached. compiler: gcc (GCC) 7.1.1 20170620 .config is attached. IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+f14b3703cd8d7670203f@syzkaller.appspotmail.com It will help syzbot understand when the bug is fixed. See footer for details. If you forward the report, please keep this part and the footer. ================================================================== BUG: KASAN: use-after-free in erspan_xmit+0x22d4/0x2430 net/ipv4/ip_gre.c:735 Read of size 2 at addr ffff8801d890fa8b by task syzkaller099344/3658 CPU: 0 PID: 3658 Comm: syzkaller099344 Not tainted 4.15.0-rc8+ #203 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 print_address_description+0x73/0x250 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report+0x25b/0x340 mm/kasan/report.c:409 __asan_report_load_n_noabort+0xf/0x20 mm/kasan/report.c:440 erspan_xmit+0x22d4/0x2430 net/ipv4/ip_gre.c:735 __netdev_start_xmit include/linux/netdevice.h:4053 [inline] netdev_start_xmit include/linux/netdevice.h:4062 [inline] packet_direct_xmit+0x3ad/0x790 net/packet/af_packet.c:267 packet_snd net/packet/af_packet.c:2944 [inline] packet_sendmsg+0x3aed/0x60b0 net/packet/af_packet.c:2969 sock_sendmsg_nosec net/socket.c:630 [inline] sock_sendmsg+0xca/0x110 net/socket.c:640 SYSC_sendto+0x361/0x5c0 net/socket.c:1721 SyS_sendto+0x40/0x50 net/socket.c:1689 entry_SYSCALL_64_fastpath+0x29/0xa0 RIP: 0033:0x4455b9 RSP: 002b:00007ffdea868098 EFLAGS: 00000217 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000000000068 RCX: 00000000004455b9 RDX: 0000000000000000 RSI: 0000000020003fd9 RDI: 0000000000000004 RBP: 00000000004a7153 R08: 0000000020008000 R09: 000000000000001c R10: 0000000000000001 R11: 0000000000000217 R12: 00000000004026f0 R13: 0000000000402780 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 3727: 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:3544 dup_mm kernel/fork.c:1187 [inline] copy_mm+0x30a/0x131b kernel/fork.c:1250 copy_process.part.38+0x1ee9/0x4b20 kernel/fork.c:1752 copy_process kernel/fork.c:1565 [inline] _do_fork+0x1f7/0xfe0 kernel/fork.c:2044 SYSC_clone kernel/fork.c:2154 [inline] SyS_clone+0x37/0x50 kernel/fork.c:2148 do_syscall_64+0x273/0x920 arch/x86/entry/common.c:285 return_from_SYSCALL_64+0x0/0x75 Freed by task 3728: 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:3488 [inline] kmem_cache_free+0x83/0x2a0 mm/slab.c:3746 __mmdrop+0x242/0x3d0 kernel/fork.c:911 mmdrop include/linux/sched/mm.h:43 [inline] __mmput kernel/fork.c:933 [inline] mmput+0x537/0x6d0 kernel/fork.c:944 exec_mmap fs/exec.c:1039 [inline] flush_old_exec+0xc8b/0x2010 fs/exec.c:1271 load_elf_binary+0x87b/0x4c10 fs/binfmt_elf.c:864 search_binary_handler+0x142/0x6b0 fs/exec.c:1638 exec_binprm fs/exec.c:1680 [inline] do_execveat_common.isra.30+0x1754/0x23c0 fs/exec.c:1802 do_execve fs/exec.c:1847 [inline] SYSC_execve fs/exec.c:1928 [inline] SyS_execve+0x39/0x50 fs/exec.c:1923 do_syscall_64+0x273/0x920 arch/x86/entry/common.c:285 return_from_SYSCALL_64+0x0/0x75 The buggy address belongs to the object at ffff8801d890f980 which belongs to the cache mm_struct of size 1440 The buggy address is located 267 bytes inside of 1440-byte region [ffff8801d890f980, ffff8801d890ff20) The buggy address belongs to the page: page:ffffea0007624380 count:1 mapcount:0 mapping:ffff8801d890e080 index:0x0 compound_mapcount: 0 flags: 0x2fffc0000008100(slab|head) raw: 02fffc0000008100 ffff8801d890e080 0000000000000000 0000000100000005 raw: ffffea0007629720 ffffea000763c5a0 ffff8801dae279c0 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801d890f980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801d890fa00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801d890fa80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^ ffff8801d890fb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801d890fb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- This bug is generated by a dumb bot. It may contain errors. See https://goo.gl/tpsmEJ for details. Direct all questions to syzkaller@googlegroups.com. syzbot will keep track of this bug report. If you forgot to add the Reported-by tag, once the fix for this bug is merged into any tree, please reply to this email with: #syz fix: exact-commit-title If you want to test a patch for this bug, please reply with: #syz test: git://repo/address.git branch and provide the patch inline or as an attachment. To mark this as a duplicate of another syzbot report, please reply with: #syz dup: exact-subject-of-another-report If it's a one-off invalid bug report, please reply with: #syz invalid Note: if the crash happens again, it will cause creation of a new bug report. Note: all commands must start from beginning of the line in the email body.