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SMTP id y4mr6902421wma.111.1601718055810; Sat, 03 Oct 2020 02:40:55 -0700 (PDT) MIME-Version: 1.0 References: <000000000000fe183705b0b1eb20@google.com> In-Reply-To: <000000000000fe183705b0b1eb20@google.com> From: Xin Long Date: Sat, 3 Oct 2020 17:56:21 +0800 Message-ID: Subject: Re: KASAN: use-after-free Read in tipc_mcast_xmit (2) To: syzbot Cc: davem , Jon Maloy , Jakub Kicinski , LKML , network dev , syzkaller-bugs , tipc-discussion@lists.sourceforge.net, Ying Xue Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 2, 2020 at 11:38 PM syzbot wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: a59cf619 Merge branch 'Fix-bugs-in-Octeontx2-netdev-driver' > git tree: bpf > console output: https://syzkaller.appspot.com/x/log.txt?x=163c2467900000 > kernel config: https://syzkaller.appspot.com/x/.config?x=99a7c78965c75e07 > dashboard link: https://syzkaller.appspot.com/bug?extid=e96a7ba46281824cc46a > compiler: gcc (GCC) 10.1.0-syz 20200507 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15ada44d900000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14007467900000 > > The issue was bisected to: > > commit ff48b6222e65ebdba5a403ef1deba6214e749193 > Author: Xin Long > Date: Sun Sep 13 11:37:31 2020 +0000 > > tipc: use skb_unshare() instead in tipc_buf_append() > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=125402b3900000 > final oops: https://syzkaller.appspot.com/x/report.txt?x=115402b3900000 > console output: https://syzkaller.appspot.com/x/log.txt?x=165402b3900000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+e96a7ba46281824cc46a@syzkaller.appspotmail.com > Fixes: ff48b6222e65 ("tipc: use skb_unshare() instead in tipc_buf_append()") > > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004028a0 > R13: 0000000000402930 R14: 0000000000000000 R15: 0000000000000000 > tipc: Failed do clone local mcast rcv buffer > ================================================================== > BUG: KASAN: use-after-free in __skb_unlink include/linux/skbuff.h:2063 [inline] > BUG: KASAN: use-after-free in __skb_dequeue include/linux/skbuff.h:2082 [inline] > BUG: KASAN: use-after-free in __skb_queue_purge include/linux/skbuff.h:2793 [inline] > BUG: KASAN: use-after-free in tipc_mcast_xmit+0xfaa/0x1170 net/tipc/bcast.c:422 > Read of size 8 at addr ffff8880a73e2040 by task syz-executor657/6887 > > CPU: 1 PID: 6887 Comm: syz-executor657 Not tainted 5.9.0-rc6-syzkaller #0 > 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+0x198/0x1fd lib/dump_stack.c:118 > print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383 > __kasan_report mm/kasan/report.c:513 [inline] > kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530 > __skb_unlink include/linux/skbuff.h:2063 [inline] > __skb_dequeue include/linux/skbuff.h:2082 [inline] > __skb_queue_purge include/linux/skbuff.h:2793 [inline] > tipc_mcast_xmit+0xfaa/0x1170 net/tipc/bcast.c:422 > tipc_sendmcast+0xaaf/0xef0 net/tipc/socket.c:865 > __tipc_sendmsg+0xee3/0x18a0 net/tipc/socket.c:1454 > tipc_sendmsg+0x4c/0x70 net/tipc/socket.c:1387 > sock_sendmsg_nosec net/socket.c:651 [inline] > sock_sendmsg+0xcf/0x120 net/socket.c:671 > ____sys_sendmsg+0x6e8/0x810 net/socket.c:2353 > ___sys_sendmsg+0xf3/0x170 net/socket.c:2407 > __sys_sendmsg+0xe5/0x1b0 net/socket.c:2440 > do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > RIP: 0033:0x4419d9 > Code: e8 cc ac 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 3b 0a fc ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007ffe0cace4c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004419d9 > RDX: 0000000000000000 RSI: 0000000020000280 RDI: 0000000000000004 > RBP: 000000000000f0ee R08: 0000000000000001 R09: 0000000000402930 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004028a0 > R13: 0000000000402930 R14: 0000000000000000 R15: 0000000000000000 > > Allocated by task 6887: > kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 > kasan_set_track mm/kasan/common.c:56 [inline] > __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461 > slab_post_alloc_hook mm/slab.h:518 [inline] > slab_alloc_node mm/slab.c:3254 [inline] > kmem_cache_alloc_node+0x136/0x430 mm/slab.c:3574 > __alloc_skb+0x71/0x550 net/core/skbuff.c:198 > alloc_skb_fclone include/linux/skbuff.h:1144 [inline] > tipc_buf_acquire+0x28/0xf0 net/tipc/msg.c:76 > tipc_msg_build+0x6b8/0x10c0 net/tipc/msg.c:428 > tipc_sendmcast+0x855/0xef0 net/tipc/socket.c:859 > __tipc_sendmsg+0xee3/0x18a0 net/tipc/socket.c:1454 > tipc_sendmsg+0x4c/0x70 net/tipc/socket.c:1387 > sock_sendmsg_nosec net/socket.c:651 [inline] > sock_sendmsg+0xcf/0x120 net/socket.c:671 > ____sys_sendmsg+0x6e8/0x810 net/socket.c:2353 > ___sys_sendmsg+0xf3/0x170 net/socket.c:2407 > __sys_sendmsg+0xe5/0x1b0 net/socket.c:2440 > do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > Freed by task 6887: > kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 > kasan_set_track+0x1c/0x30 mm/kasan/common.c:56 > kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355 > __kasan_slab_free+0xd8/0x120 mm/kasan/common.c:422 > __cache_free mm/slab.c:3418 [inline] > kmem_cache_free.part.0+0x74/0x1e0 mm/slab.c:3693 > kfree_skbmem+0x166/0x1b0 net/core/skbuff.c:643 > kfree_skb+0x7d/0x100 include/linux/refcount.h:270 > tipc_buf_append+0x6dc/0xcf0 net/tipc/msg.c:198 > tipc_msg_reassemble+0x175/0x4f0 net/tipc/msg.c:790 > tipc_mcast_xmit+0x699/0x1170 net/tipc/bcast.c:386 > tipc_sendmcast+0xaaf/0xef0 net/tipc/socket.c:865 > __tipc_sendmsg+0xee3/0x18a0 net/tipc/socket.c:1454 > tipc_sendmsg+0x4c/0x70 net/tipc/socket.c:1387 > sock_sendmsg_nosec net/socket.c:651 [inline] > sock_sendmsg+0xcf/0x120 net/socket.c:671 > ____sys_sendmsg+0x6e8/0x810 net/socket.c:2353 > ___sys_sendmsg+0xf3/0x170 net/socket.c:2407 > __sys_sendmsg+0xe5/0x1b0 net/socket.c:2440 > do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 in tipc_msg_reassemble(): if ((&head, &frag)) break; if (!head) goto error; <--- [1] } __skb_queue_tail(rcvq, frag); return true; error: pr_warn("Failed do clone local mcast rcv buffer\n"); kfree_skb(head); <---[2] return false; when head is NULL at [1], it goes [2] and could cause a crash. from the log, we can see "Failed do clone local mcast rcv buffer" as well. will check and make a fix for this. Thanks. > > The buggy address belongs to the object at ffff8880a73e2040 > which belongs to the cache skbuff_fclone_cache of size 456 > The buggy address is located 0 bytes inside of > 456-byte region [ffff8880a73e2040, ffff8880a73e2208) > The buggy address belongs to the page: > page:000000001368f319 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xa73e2 > flags: 0xfffe0000000200(slab) > raw: 00fffe0000000200 ffff8880a9050f50 ffffea00028ff188 ffff8880a903dc00 > raw: 0000000000000000 ffff8880a73e2040 0000000100000006 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff8880a73e1f00: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc > ffff8880a73e1f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > >ffff8880a73e2000: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb > ^ > ffff8880a73e2080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8880a73e2100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > syzbot can test patches for this issue, for details see: > https://goo.gl/tpsmEJ#testing-patches