Re: [syzbot] WARNING: kmalloc bug in hash_net_create

[Jozsef Kadlecsik]

Hi Eric,

On Fri, 3 Sep 2021, Eric Dumazet wrote:

> On 9/3/21 4:50 PM, syzbot wrote:
> > Hello,
> > 
> > syzbot found the following issue on:
> > 
> > HEAD commit:    a9c9a6f741cd Merge tag 'scsi-misc' of git://git.kernel.org..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=117f0915300000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=1ac29107aeb2a552
> > dashboard link: https://syzkaller.appspot.com/bug?extid=2b8443c35458a617c904
> > compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12fba55d300000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15bd2f49300000
> > 
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+2b8443c35458a617c904@xxxxxxxxxxxxxxxxxxxxxxxxx
> > 
> > ------------[ cut here ]------------
> > WARNING: CPU: 0 PID: 8432 at mm/util.c:597 kvmalloc_node+0x111/0x120 mm/util.c:597
> > Modules linked in:
> > CPU: 0 PID: 8432 Comm: syz-executor044 Not tainted 5.14.0-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > RIP: 0010:kvmalloc_node+0x111/0x120 mm/util.c:597
> > Code: 01 00 00 00 4c 89 e7 e8 ed 11 0d 00 49 89 c5 e9 69 ff ff ff e8 90 55 d1 ff 41 89 ed 41 81 cd 00 20 01 00 eb 95 e8 7f 55 d1 ff <0f> 0b e9 4c ff ff ff 0f 1f 84 00 00 00 00 00 55 48 89 fd 53 e8 66
> > RSP: 0018:ffffc900018f7288 EFLAGS: 00010293
> > RAX: 0000000000000000 RBX: ffffc900018f73a0 RCX: 0000000000000000
> > RDX: ffff88803d6ca300 RSI: ffffffff81a3f651 RDI: 0000000000000003
> > RBP: 0000000000400dc0 R08: 000000007fffffff R09: 000000000000001f
> > R10: ffffffff81a3f60e R11: 000000000000001f R12: 0000000400000018
> > R13: 0000000000000000 R14: 00000000ffffffff R15: ffff88801743d000
> > FS:  0000000001d7c300(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 0000000020000046 CR3: 000000001e0d4000 CR4: 00000000001506f0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > Call Trace:
> >  hash_net_create+0x3dd/0x1220 net/netfilter/ipset/ip_set_hash_gen.h:1524
> >  ip_set_create+0x782/0x15a0 net/netfilter/ipset/ip_set_core.c:1100
> >  nfnetlink_rcv_msg+0xbc9/0x13f0 net/netfilter/nfnetlink.c:296
> >  netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
> >  nfnetlink_rcv+0x1ac/0x420 net/netfilter/nfnetlink.c:654
> >  netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
> >  netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
> >  netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929
> >  sock_sendmsg_nosec net/socket.c:704 [inline]
> >  sock_sendmsg+0xcf/0x120 net/socket.c:724
> >  ____sys_sendmsg+0x6e8/0x810 net/socket.c:2409
> >  ___sys_sendmsg+0xf3/0x170 net/socket.c:2463
> >  __sys_sendmsg+0xe5/0x1b0 net/socket.c:2492
> >  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> >  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
> >  entry_SYSCALL_64_after_hwframe+0x44/0xae
> > RIP: 0033:0x43f039
> > Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
> > RSP: 002b:00007ffc97697a28 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> > RAX: ffffffffffffffda RBX: 0000000000400488 RCX: 000000000043f039
> > RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000000000003
> > RBP: 0000000000403020 R08: 0000000000000005 R09: 0000000000400488
> > R10: 0000000000000002 R11: 0000000000000246 R12: 00000000004030b0
> > R13: 0000000000000000 R14: 00000000004ac018 R15: 0000000000400488
> > 
> > 
> > ---
> > 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@xxxxxxxxxxxxxxxx.
> > 
> > syzbot will keep track of this issue. See:
> > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> > syzbot can test patches for this issue, for details see:
> > https://goo.gl/tpsmEJ#testing-patches
> > 
> 
> As mentioned to Linus earlier, this bug comes after recent patch

Thanks indeed, that made simpler to fix it.

Best regards,
Jozsef

> commit 7661809d493b426e979f39ab512e3adf41fbcc69
> Author: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Date:   Wed Jul 14 09:45:49 2021 -0700
> 
>     mm: don't allow oversized kvmalloc() calls
>     
>     'kvmalloc()' is a convenience function for people who want to do a
>     kmalloc() but fall back on vmalloc() if there aren't enough physically
>     contiguous pages, or if the allocation is larger than what kmalloc()
>     supports.
>     
>     However, let's make sure it doesn't get _too_ easy to do crazy things
>     with it.  In particular, don't allow big allocations that could be due
>     to integer overflow or underflow.  So make sure the allocation size fits
>     in an 'int', to protect against trivial integer conversion issues.
>     
>     Acked-by: Willy Tarreau <w@xxxxxx>
>     Cc: Kees Cook <keescook@xxxxxxxxxxxx>
>     Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> 

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