On Sat, Mar 14, 2020 at 10:51 AM Qiujun Huang <anenbupt@xxxxxxxxx> wrote: > > For geo segment sob, we shouldn't subtract the sizeof(struct > scup_chunk) in scup_wfree. For gso segment skb, we shouldn't subtract the sizeof(struct sctp_chunk) in sctp_wfree. Sorry about the typos. Thanks! > > diff --git a/net/sctp/socket.c b/net/sctp/socket.c > index fed26a1e9518..e0cc5d7c88fb 100644 > --- a/net/sctp/socket.c > +++ b/net/sctp/socket.c > @@ -9085,7 +9085,9 @@ static void sctp_wfree(struct sk_buff *skb) > sk_mem_uncharge(sk, skb->truesize); > sk->sk_wmem_queued -= skb->truesize + sizeof(struct sctp_chunk); > asoc->sndbuf_used -= skb->truesize + sizeof(struct sctp_chunk); > - WARN_ON(refcount_sub_and_test(sizeof(struct sctp_chunk), > + > + if (skb_is_gso(skb)) > + WARN_ON(refcount_sub_and_test(sizeof(struct sctp_chunk), > &sk->sk_wmem_alloc)); > > On Wed, Mar 11, 2020 at 11:00 PM Qiujun Huang <anenbupt@xxxxxxxxx> wrote: > > > > sctp_wfree > > ->refcount_sub_and_test(sizeof(struct sctp_chunk), > > &sk->sk_wmem_alloc) > > sctp_wfree will sub sizeof(struct sctp_chunk) for every skb. So could > > we add the extra size for gso segment ? > > > > > > > > --- a/net/sctp/output.c > > +++ b/net/sctp/output.c > > @@ -398,7 +398,8 @@ static void sctp_packet_gso_append(struct sk_buff > > *head, struct sk_buff *skb) > > head->truesize += skb->truesize; > > head->data_len += skb->len; > > head->len += skb->len; > > - refcount_add(skb->truesize, &head->sk->sk_wmem_alloc); > > + refcount_add(skb->truesize + sizeof(struct sctp_chunk), > > + &head->sk->sk_wmem_alloc); > > > > __skb_header_release(skb); > > > > On Tue, Mar 10, 2020 at 9:36 AM syzbot > > <syzbot+cea71eec5d6de256d54d@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > > > Hello, > > > > > > syzbot found the following crash on: > > > > > > HEAD commit: 2c523b34 Linux 5.6-rc5 > > > git tree: upstream > > > console output: https://syzkaller.appspot.com/x/log.txt?x=155a5f29e00000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=a5295e161cd85b82 > > > dashboard link: https://syzkaller.appspot.com/bug?extid=cea71eec5d6de256d54d > > > compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=164b5181e00000 > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=166dd70de00000 > > > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > > Reported-by: syzbot+cea71eec5d6de256d54d@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > > > ------------[ cut here ]------------ > > > refcount_t: underflow; use-after-free. > > > WARNING: CPU: 1 PID: 8668 at lib/refcount.c:28 refcount_warn_saturate+0x15b/0x1a0 lib/refcount.c:28 > > > Kernel panic - not syncing: panic_on_warn set ... > > > CPU: 1 PID: 8668 Comm: syz-executor779 Not tainted 5.6.0-rc5-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+0x1e9/0x30e lib/dump_stack.c:118 > > > panic+0x264/0x7a0 kernel/panic.c:221 > > > __warn+0x209/0x210 kernel/panic.c:582 > > > report_bug+0x1ac/0x2d0 lib/bug.c:195 > > > fixup_bug arch/x86/kernel/traps.c:174 [inline] > > > do_error_trap+0xca/0x1c0 arch/x86/kernel/traps.c:267 > > > do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286 > > > invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027 > > > RIP: 0010:refcount_warn_saturate+0x15b/0x1a0 lib/refcount.c:28 > > > Code: c7 e4 ff d0 88 31 c0 e8 23 20 b3 fd 0f 0b eb 85 e8 8a 4a e0 fd c6 05 ff 70 b1 05 01 48 c7 c7 10 00 d1 88 31 c0 e8 05 20 b3 fd <0f> 0b e9 64 ff ff ff e8 69 4a e0 fd c6 05 df 70 b1 05 01 48 c7 c7 > > > RSP: 0018:ffffc90001f577d0 EFLAGS: 00010246 > > > RAX: 8c9c9070bbb4e500 RBX: 0000000000000003 RCX: ffff8880938a63c0 > > > RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000 > > > RBP: 0000000000000003 R08: ffffffff815e16e6 R09: fffffbfff15db92a > > > R10: fffffbfff15db92a R11: 0000000000000000 R12: dffffc0000000000 > > > R13: ffff88809de82000 R14: ffff8880a89237c0 R15: 1ffff11013be52b0 > > > sctp_wfree+0x3b1/0x710 net/sctp/socket.c:9111 > > > skb_release_head_state+0xfb/0x210 net/core/skbuff.c:651 > > > skb_release_all net/core/skbuff.c:662 [inline] > > > __kfree_skb+0x22/0x1c0 net/core/skbuff.c:678 > > > sctp_chunk_destroy net/sctp/sm_make_chunk.c:1454 [inline] > > > sctp_chunk_put+0x17b/0x200 net/sctp/sm_make_chunk.c:1481 > > > __sctp_outq_teardown+0x80a/0x9d0 net/sctp/outqueue.c:257 > > > sctp_association_free+0x21e/0x7c0 net/sctp/associola.c:339 > > > sctp_cmd_delete_tcb net/sctp/sm_sideeffect.c:930 [inline] > > > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1318 [inline] > > > sctp_side_effects net/sctp/sm_sideeffect.c:1185 [inline] > > > sctp_do_sm+0x3c01/0x5560 net/sctp/sm_sideeffect.c:1156 > > > sctp_primitive_ABORT+0x93/0xc0 net/sctp/primitive.c:104 > > > sctp_close+0x231/0x770 net/sctp/socket.c:1512 > > > inet_release+0x135/0x180 net/ipv4/af_inet.c:427 > > > __sock_release net/socket.c:605 [inline] > > > sock_close+0xd8/0x260 net/socket.c:1283 > > > __fput+0x2d8/0x730 fs/file_table.c:280 > > > task_work_run+0x176/0x1b0 kernel/task_work.c:113 > > > exit_task_work include/linux/task_work.h:22 [inline] > > > do_exit+0x5ef/0x1f80 kernel/exit.c:801 > > > do_group_exit+0x15e/0x2c0 kernel/exit.c:899 > > > __do_sys_exit_group+0x13/0x20 kernel/exit.c:910 > > > __se_sys_exit_group+0x10/0x10 kernel/exit.c:908 > > > __x64_sys_exit_group+0x37/0x40 kernel/exit.c:908 > > > do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:294 > > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > RIP: 0033:0x43ef98 > > > Code: Bad RIP value. > > > RSP: 002b:00007ffcc7e7c398 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 > > > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ef98 > > > RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 > > > RBP: 00000000004be7a8 R08: 00000000000000e7 R09: ffffffffffffffd0 > > > R10: 000000002059aff8 R11: 0000000000000246 R12: 0000000000000001 > > > R13: 00000000006d01a0 R14: 0000000000000000 R15: 0000000000000000 > > > Kernel Offset: disabled > > > Rebooting in 86400 seconds.. > > > > > > > > > --- > > > This bug 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@xxxxxxxxxxxxxxxx. > > > > > > syzbot will keep track of this bug report. See: > > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > > syzbot can test patches for this bug, for details see: > > > https://goo.gl/tpsmEJ#testing-patches
