WARNING in xt_compat_add_offset

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 8a61716ff2ab Merge tag 'ceph-for-5.0-rc8' of git://github...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1456fa6cc00000
kernel config: https://syzkaller.appspot.com/x/.config?x=7132344728e7ec3f
dashboard link: https://syzkaller.appspot.com/bug?extid=276ddebab3382bbf72db
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
userspace arch: i386
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=140c0914c00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+276dde...@syzkaller.appspotmail.com

IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): hsr0: link becomes ready
8021q: adding VLAN 0 to HW filter on device batadv0
cannot load conntrack support for proto=7
WARNING: CPU: 1 PID: 7458 at net/netfilter/x_tables.c:654
xt_compat_add_offset+0x22a/0x290 net/netfilter/x_tables.c:654
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 7458 Comm: syz-executor.0 Not tainted 5.0.0-rc7+ #83
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+0x172/0x1f0 lib/dump_stack.c:113
panic+0x2cb/0x65c kernel/panic.c:214
__warn.cold+0x20/0x45 kernel/panic.c:571
report_bug+0x263/0x2b0 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:178 [inline]
fixup_bug arch/x86/kernel/traps.c:173 [inline]
do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271
do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:290
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:973
RIP: 0010:xt_compat_add_offset+0x22a/0x290 net/netfilter/x_tables.c:654
Code: 00 01 e8 59 67 bb fb 44 89 e0 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f
5d c3 e8 42 67 bb fb 0f 0b e9 56 fe ff ff e8 36 67 bb fb <0f> 0b 41 bc f4
ff ff ff eb ce 4c 89 f7 e8 14 6a f2 fb e9 75 ff ff
RSP: 0018:ffff8880a8197808 EFLAGS: 00010293
RAX: ffff88809055e040 RBX: ffff8882166548d0 RCX: ffffffff85b47892
RDX: 0000000000000000 RSI: ffffffff85b47a4a RDI: ffff8882166549f0
RBP: ffff8880a8197838 R08: ffff88809055e040 R09: ffffed1042cca92f
R10: ffffed1042cca92e R11: ffff888216654977 R12: 0000000000000018
R13: 0000000000000030 R14: ffff88809055e040 R15: 0000000000000000
size_entry_mwt net/bridge/netfilter/ebtables.c:2183 [inline]
compat_copy_entries+0x51b/0x1360 net/bridge/netfilter/ebtables.c:2208
compat_do_replace+0x3b3/0x680 net/bridge/netfilter/ebtables.c:2302
compat_do_ebt_set_ctl+0x229/0x278 net/bridge/netfilter/ebtables.c:2384
compat_nf_sockopt net/netfilter/nf_sockopt.c:144 [inline]
compat_nf_setsockopt+0x9b/0x140 net/netfilter/nf_sockopt.c:156
compat_ip_setsockopt net/ipv4/ip_sockglue.c:1284 [inline]
compat_ip_setsockopt+0x106/0x140 net/ipv4/ip_sockglue.c:1265
compat_udp_setsockopt+0x68/0xb0 net/ipv4/udp.c:2629
compat_ipv6_setsockopt+0xca/0x210 net/ipv6/ipv6_sockglue.c:959
inet_csk_compat_setsockopt+0x99/0x120 net/ipv4/inet_connection_sock.c:1054
compat_tcp_setsockopt+0x4d/0x80 net/ipv4/tcp.c:3079
compat_sock_common_setsockopt+0xb4/0x150 net/core/sock.c:3002
__compat_sys_setsockopt+0x176/0x610 net/compat.c:404
__do_compat_sys_setsockopt net/compat.c:417 [inline]
__se_compat_sys_setsockopt net/compat.c:414 [inline]
__ia32_compat_sys_setsockopt+0xbd/0x150 net/compat.c:414
do_syscall_32_irqs_on arch/x86/entry/common.c:326 [inline]
do_fast_syscall_32+0x281/0xc98 arch/x86/entry/common.c:397
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7fd3869
Code: 85 d2 74 02 89 0a 5b 5d c3 8b 04 24 c3 8b 14 24 c3 8b 3c 24 c3 90 90
90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90
90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000f7fcf0cc EFLAGS: 00000296 ORIG_RAX: 000000000000016e
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000000000
RDX: 0000000000000080 RSI: 00000000200000c0 RDI: 0000000000000270
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
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[syzbot]

syzbot has bisected this bug to:

commit 2035f3ff8eaa29cfb5c8e2160b0f6e85eeb21a95
Author: Florian Westphal <f...@strlen.de>
Date: Mon Jan 21 20:54:36 2019 +0000

netfilter: ebtables: compat: un-break 32bit setsockopt when no rules
are present

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1462834d200000
start commit: 8a61716f Merge tag 'ceph-for-5.0-rc8' of git://github.com/..
git tree: upstream
final crash: https://syzkaller.appspot.com/x/report.txt?x=1662834d200000
console output: https://syzkaller.appspot.com/x/log.txt?x=1262834d200000

kernel config: https://syzkaller.appspot.com/x/.config?x=7132344728e7ec3f
dashboard link: https://syzkaller.appspot.com/bug?extid=276ddebab3382bbf72db

userspace arch: i386
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=140c0914c00000

Reported-by: syzbot+276dde...@syzkaller.appspotmail.com
Fixes: 2035f3ff8eaa ("netfilter: ebtables: compat: un-break 32bit
setsockopt when no rules are present")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: abdfd52a Merge tag 'armsoc-defconfig' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=146c4968600000
kernel config: https://syzkaller.appspot.com/x/.config?x=b8e53b1e149c0183

dashboard link: https://syzkaller.appspot.com/bug?extid=276ddebab3382bbf72db
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
userspace arch: i386

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=159be500600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=139364f0600000

The bug was bisected to:

commit 2035f3ff8eaa29cfb5c8e2160b0f6e85eeb21a95
Author: Florian Westphal <f...@strlen.de>
Date: Mon Jan 21 20:54:36 2019 +0000

netfilter: ebtables: compat: un-break 32bit setsockopt when no rules
are present

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1462834d200000

final crash: https://syzkaller.appspot.com/x/report.txt?x=1662834d200000
console output: https://syzkaller.appspot.com/x/log.txt?x=1262834d200000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+276dde...@syzkaller.appspotmail.com

Fixes: 2035f3ff8eaa ("netfilter: ebtables: compat: un-break 32bit
setsockopt when no rules are present")

------------[ cut here ]------------
WARNING: CPU: 1 PID: 9012 at net/netfilter/x_tables.c:649
xt_compat_add_offset.cold+0x11/0x36 /net/netfilter/x_tables.c:649

Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 9012 Comm: syz-executor131 Not tainted 5.2.0+ #64

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+0x172/0x1f0 /lib/dump_stack.c:113
panic+0x2dc/0x755 /kernel/panic.c:219
__warn.cold+0x20/0x4c /kernel/panic.c:576
report_bug+0x263/0x2b0 /lib/bug.c:186
fixup_bug /arch/x86/kernel/traps.c:179 [inline]
fixup_bug /arch/x86/kernel/traps.c:174 [inline]
do_error_trap+0x11b/0x200 /arch/x86/kernel/traps.c:272
do_invalid_op+0x37/0x50 /arch/x86/kernel/traps.c:291
invalid_op+0x14/0x20 /arch/x86/entry/entry_64.S:1008
RIP: 0010:xt_compat_add_offset.cold+0x11/0x36 /net/netfilter/x_tables.c:649
Code: 89 ee 48 c7 c7 c0 29 2d 88 e8 0c 76 7b fb 41 bc ea ff ff ff e9 87 88
ff ff e8 08 d3 91 fb 48 c7 c7 00 2a 2d 88 e8 f0 75 7b fb <0f> 0b 41 bc f4
ff ff ff e9 01 8b ff ff e8 ea d2 91 fb 48 c7 c7 00
RSP: 0018:ffff8880a382f8d8 EFLAGS: 00010286
RAX: 0000000000000024 RBX: ffff888216b74ad0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815c3a26 RDI: ffffed1014705f0d
RBP: ffff8880a382f908 R08: 0000000000000024 R09: ffffed1015d260b1
R10: ffffed1015d260b0 R11: ffff8880ae930587 R12: 0000000000000014
R13: 0000000000000060 R14: ffff88808b7b6180 R15: 0000000000000000
size_entry_mwt /net/bridge/netfilter/ebtables.c:2122 [inline]
compat_copy_entries+0x10e9/0x1340 /net/bridge/netfilter/ebtables.c:2147
compat_do_replace+0x3b3/0x680 /net/bridge/netfilter/ebtables.c:2243
compat_do_ebt_set_ctl+0x22f/0x27e /net/bridge/netfilter/ebtables.c:2325
compat_nf_sockopt /net/netfilter/nf_sockopt.c:144 [inline]
compat_nf_setsockopt+0x98/0x140 /net/netfilter/nf_sockopt.c:156
compat_ip_setsockopt /net/ipv4/ip_sockglue.c:1286 [inline]
compat_ip_setsockopt+0x106/0x140 /net/ipv4/ip_sockglue.c:1267
compat_raw_setsockopt+0xe0/0x100 /net/ipv4/raw.c:865
compat_sock_common_setsockopt+0xb2/0x140 /net/core/sock.c:3141
__compat_sys_setsockopt+0x185/0x380 /net/compat.c:384
__do_compat_sys_setsockopt /net/compat.c:397 [inline]
__se_compat_sys_setsockopt /net/compat.c:394 [inline]
__ia32_compat_sys_setsockopt+0xbd/0x150 /net/compat.c:394
do_syscall_32_irqs_on /arch/x86/entry/common.c:332 [inline]
do_fast_syscall_32+0x27b/0xdb3 /arch/x86/entry/common.c:403
entry_SYSENTER_compat+0x70/0x7f /arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f489c9
Code: d3 83 c4 10 5b 5e 5d c3 ba 80 96 98 00 eb a9 8b 04 24 c3 8b 34 24 c3
8b 3c 24 c3 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90

90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90

RSP: 002b:00000000ffaa6d8c EFLAGS: 00000292 ORIG_RAX: 000000000000016e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000000000
RDX: 0000000000000080 RSI: 0000000020000000 RDI: 00000000000001fc
RBP: 0000000000000012 R08: 0000000000000000 R09: 0000000000000000

[Florian Westphal]

ebtables doesn't include the base chain policies in the rule count,
so we need to add them manually when we call into the x_tables core
to allocate space for the comapt offset table.

This lead syzbot to trigger:

WARNING: CPU: 1 PID: 9012 at net/netfilter/x_tables.c:649

xt_compat_add_offset.cold+0x11/0x36 net/netfilter/x_tables.c:649

Reported-by: syzbot+276dde...@syzkaller.appspotmail.com
Fixes: 2035f3ff8eaa ("netfilter: ebtables: compat: un-break 32bit setsockopt when no rules are present")

Signed-off-by: Florian Westphal <f...@strlen.de>
---
net/bridge/netfilter/ebtables.c | 28 +++++++++++++++++-----------
1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index fd84b48e48b5..c8177a89f52c 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -1770,20 +1770,28 @@ static int compat_calc_entry(const struct ebt_entry *e,
return 0;
}

+static int ebt_compat_init_offsets(unsigned int number)
+{
+ if (number > INT_MAX)
+ return -EINVAL;
+
+ /* also count the base chain policies */
+ number += NF_BR_NUMHOOKS;
+
+ return xt_compat_init_offsets(NFPROTO_BRIDGE, number);
+}

static int compat_table_info(const struct ebt_table_info *info,
struct compat_ebt_replace *newinfo)
{
unsigned int size = info->entries_size;
const void *entries = info->entries;
+ int ret;

newinfo->entries_size = size;
- if (info->nentries) {
- int ret = xt_compat_init_offsets(NFPROTO_BRIDGE,
- info->nentries);
- if (ret)
- return ret;
- }
+ ret = ebt_compat_init_offsets(info->nentries);
+ if (ret)
+ return ret;

return EBT_ENTRY_ITERATE(entries, size, compat_calc_entry, info,
entries, newinfo);
@@ -2234,11 +2242,9 @@ static int compat_do_replace(struct net *net, void __user *user,

xt_compat_lock(NFPROTO_BRIDGE);

- if (tmp.nentries) {
- ret = xt_compat_init_offsets(NFPROTO_BRIDGE, tmp.nentries);
- if (ret < 0)
- goto out_unlock;
- }
+ ret = ebt_compat_init_offsets(tmp.nentries);
+ if (ret < 0)
+ goto out_unlock;

ret = compat_copy_entries(entries_tmp, tmp.entries_size, &state);
if (ret < 0)
--
2.21.0

[Pablo Neira Ayuso]

On Mon, Jul 29, 2019 at 05:58:10PM +0200, Florian Westphal wrote:
> ebtables doesn't include the base chain policies in the rule count,
> so we need to add them manually when we call into the x_tables core
> to allocate space for the comapt offset table.
>
> This lead syzbot to trigger:
> WARNING: CPU: 1 PID: 9012 at net/netfilter/x_tables.c:649
> xt_compat_add_offset.cold+0x11/0x36 net/netfilter/x_tables.c:649

Applied, thanks Florian.