KASAN: use-after-free Read in pppol2tp_connect
From: syzbot <hidden>
Date: 2018-01-16 03:58:05
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Hello, syzkaller hit the following crash on b625c1ff82272e26c76570d3c7123419ec345b20 git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master compiler: gcc (GCC) 7.1.1 20170620 .config is attached Raw console output is attached. C reproducer is attached syzkaller reproducer is attached. See https://goo.gl/kgGztJ for information about syzkaller reproducers IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+9df43faf09bd400f2993@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 __read_once_size include/linux/compiler.h:188 [inline] BUG: KASAN: use-after-free in sk_dst_get include/net/sock.h:1768 [inline] BUG: KASAN: use-after-free in pppol2tp_session_init net/l2tp/l2tp_ppp.c:596 [inline] BUG: KASAN: use-after-free in pppol2tp_connect+0x1a91/0x1dd0 net/l2tp/l2tp_ppp.c:756 Read of size 8 at addr ffff8801c2c402a8 by task syzkaller472056/4457 CPU: 0 PID: 4457 Comm: syzkaller472056 Not tainted 4.15.0-rc7-next-20180115+ #97 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:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report+0x23b/0x360 mm/kasan/report.c:412 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 __read_once_size include/linux/compiler.h:188 [inline] sk_dst_get include/net/sock.h:1768 [inline] pppol2tp_session_init net/l2tp/l2tp_ppp.c:596 [inline] pppol2tp_connect+0x1a91/0x1dd0 net/l2tp/l2tp_ppp.c:756 SYSC_connect+0x213/0x4a0 net/socket.c:1613 SyS_connect+0x24/0x30 net/socket.c:1594 entry_SYSCALL_64_fastpath+0x29/0xa0 RIP: 0033:0x445c69 RSP: 002b:00007f200cbabdb8 EFLAGS: 00000297 ORIG_RAX: 000000000000002a RAX: ffffffffffffffda RBX: 00000000006dbc24 RCX: 0000000000445c69 RDX: 000000000000002e RSI: 00000000205fafd2 RDI: 0000000000000005 RBP: 00000000006dbc20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000297 R12: 0000000000000000 R13: 00007ffc2560dabf R14: 00007f200cbac9c0 R15: 0000000000000005 Allocated by task 4454: 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:552 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3541 sk_prot_alloc+0x65/0x2a0 net/core/sock.c:1465 sk_alloc+0x105/0x1440 net/core/sock.c:1525 inet6_create+0x44d/0x10f0 net/ipv6/af_inet6.c:183 __sock_create+0x4d4/0x850 net/socket.c:1259 sock_create net/socket.c:1299 [inline] SYSC_socket net/socket.c:1329 [inline] SyS_socket+0xeb/0x1d0 net/socket.c:1309 entry_SYSCALL_64_fastpath+0x29/0xa0 Freed by task 4457: save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527 __cache_free mm/slab.c:3485 [inline] kmem_cache_free+0x86/0x2b0 mm/slab.c:3743 sk_prot_free net/core/sock.c:1506 [inline] __sk_destruct+0x622/0x910 net/core/sock.c:1590 sk_destruct+0x47/0x80 net/core/sock.c:1598 __sk_free+0xf1/0x2b0 net/core/sock.c:1609 sk_free+0x2a/0x40 net/core/sock.c:1620 sock_put include/net/sock.h:1660 [inline] l2tp_session_free+0x21c/0x2b0 net/l2tp/l2tp_core.c:1665 l2tp_session_dec_refcount net/l2tp/l2tp_core.h:302 [inline] pppol2tp_session_destruct+0xd4/0x110 net/l2tp/l2tp_ppp.c:448 __sk_destruct+0xfd/0x910 net/core/sock.c:1563 sk_destruct+0x47/0x80 net/core/sock.c:1598 __sk_free+0xf1/0x2b0 net/core/sock.c:1609 sk_free+0x2a/0x40 net/core/sock.c:1620 sock_put include/net/sock.h:1660 [inline] pppol2tp_put_sk+0x49/0x60 net/l2tp/l2tp_ppp.c:457 __rcu_reclaim kernel/rcu/rcu.h:172 [inline] rcu_do_batch kernel/rcu/tree.c:2674 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2933 [inline] __rcu_process_callbacks kernel/rcu/tree.c:2900 [inline] rcu_process_callbacks+0xd6c/0x17f0 kernel/rcu/tree.c:2917 __do_softirq+0x2d7/0xb85 kernel/softirq.c:285 The buggy address belongs to the object at ffff8801c2c40080 which belongs to the cache UDPv6 of size 1664 The buggy address is located 552 bytes inside of 1664-byte region [ffff8801c2c40080, ffff8801c2c40700) The buggy address belongs to the page: page:ffffea00070b1000 count:1 mapcount:0 mapping:ffff8801c2c40080 index:0x0 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffff8801c2c40080 0000000000000000 0000000100000002 raw: ffffea0007624fe0 ffffea000760c820 ffff8801d3379840 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801c2c40180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801c2c40200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801c2c40280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^ ffff8801c2c40300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801c2c40380: 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.