[syzbot] [net?] general protection fault in htb_tcf_block

[syzbot] [net?] general protection fault in htb_tcf_block

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    c2b2ee36250d bridge: cfm: fix enum typo in br_cc_ccm_tx_pa..
git tree:       net-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=13caf96ee80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a4e9ca8e3c104d2a
dashboard link: https://syzkaller.appspot.com/bug?extid=806b0572c8d06b66b234
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16b63e09e80000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1041287ee80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7344dc892eab/disk-c2b2ee36.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b5d04995c162/vmlinux-c2b2ee36.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9558856ab7f4/bzImage-c2b2ee36.xz

The issue was bisected to:

commit 913b47d3424e7d99eaf34b798c47dfa840c64a08
Author: Victor Nogueira <victor@mojatatu.com>
Date:   Tue Dec 19 18:16:19 2023 +0000

    net/sched: Introduce tc block netdev tracking infra

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=15a5c1cee80000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=17a5c1cee80000
console output: https://syzkaller.appspot.com/x/log.txt?x=13a5c1cee80000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+806b0572c8d06b66b234@syzkaller.appspotmail.com
Fixes: 913b47d3424e ("net/sched: Introduce tc block netdev tracking infra")

general protection fault, probably for non-canonical address 0xdffffc000000200c: 0000 [#1] PREEMPT SMP KASAN
KASAN: probably user-memory-access in range [0x0000000000010060-0x0000000000010067]
CPU: 1 PID: 5060 Comm: syz-executor136 Not tainted 6.7.0-rc6-syzkaller-01658-gc2b2ee36250d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
RIP: 0010:htb_tcf_block+0x3a/0xa0 net/sched/sch_htb.c:2093
Code: f8 31 ff 48 89 de e8 f5 4f f1 f8 48 85 db 74 2f e8 5b 54 f1 f8 48 8d 7b 70 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 4b 48 8b 5b 70 e8 37 54 f1 f8 48 89 d8 5b 5d c3 e8
RSP: 0018:ffffc9000390f408 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 000000000000fff2 RCX: ffffffff88962d0b
RDX: 000000000000200c RSI: ffffffff88962d15 RDI: 0000000000010062
RBP: ffff888074ee6000 R08: 0000000000000007 R09: 0000000000000000
R10: 000000000000fff2 R11: ffffffff81de56d2 R12: ffff88807f154000
R13: ffffffff8bed4a60 R14: 0000000000000001 R15: ffffffff8f19a9a0
FS:  0000555556d17380(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020005840 CR3: 00000000762cd000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 qdisc_block_add_dev net/sched/sch_api.c:1190 [inline]
 qdisc_create+0x6b6/0x1430 net/sched/sch_api.c:1390
 tc_modify_qdisc+0x4d5/0x1c30 net/sched/sch_api.c:1788
 rtnetlink_rcv_msg+0x3c7/0xe00 net/core/rtnetlink.c:6615
 netlink_rcv_skb+0x16b/0x440 net/netlink/af_netlink.c:2543
 netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline]
 netlink_unicast+0x53b/0x810 net/netlink/af_netlink.c:1367
 netlink_sendmsg+0x8b7/0xd70 net/netlink/af_netlink.c:1908
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0xd5/0x180 net/socket.c:745
 ____sys_sendmsg+0x6ac/0x940 net/socket.c:2584
 ___sys_sendmsg+0x135/0x1d0 net/socket.c:2638
 __sys_sendmsg+0x117/0x1e0 net/socket.c:2667
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f0719e9b779
Code: 48 83 c4 28 c3 e8 27 18 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc30cf03a8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f0719ee402d RCX: 00007f0719e9b779
RDX: 0000000000000000 RSI: 0000000020005840 RDI: 0000000000000003
RBP: 00007ffc30cf03c0 R08: 00007ffc30cf0420 R09: 00007ffc30cf0420
R10: 00007ffc30cf0420 R11: 0000000000000246 R12: 00007f0719f0e5f0
R13: 00007ffc30cf05a8 R14: 0000000000000001 R15: 0000000000000001
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:htb_tcf_block+0x3a/0xa0 net/sched/sch_htb.c:2093
Code: f8 31 ff 48 89 de e8 f5 4f f1 f8 48 85 db 74 2f e8 5b 54 f1 f8 48 8d 7b 70 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 4b 48 8b 5b 70 e8 37 54 f1 f8 48 89 d8 5b 5d c3 e8
RSP: 0018:ffffc9000390f408 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 000000000000fff2 RCX: ffffffff88962d0b
RDX: 000000000000200c RSI: ffffffff88962d15 RDI: 0000000000010062
RBP: ffff888074ee6000 R08: 0000000000000007 R09: 0000000000000000
R10: 000000000000fff2 R11: ffffffff81de56d2 R12: ffff88807f154000
R13: ffffffff8bed4a60 R14: 0000000000000001 R15: ffffffff8f19a9a0
FS:  0000555556d17380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000562b45e47ba0 CR3: 00000000762cd000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	f8                   	clc
   1:	31 ff                	xor    %edi,%edi
   3:	48 89 de             	mov    %rbx,%rsi
   6:	e8 f5 4f f1 f8       	call   0xf8f15000
   b:	48 85 db             	test   %rbx,%rbx
   e:	74 2f                	je     0x3f
  10:	e8 5b 54 f1 f8       	call   0xf8f15470
  15:	48 8d 7b 70          	lea    0x70(%rbx),%rdi
  19:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  20:	fc ff df
  23:	48 89 fa             	mov    %rdi,%rdx
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2e:	75 4b                	jne    0x7b
  30:	48 8b 5b 70          	mov    0x70(%rbx),%rbx
  34:	e8 37 54 f1 f8       	call   0xf8f15470
  39:	48 89 d8             	mov    %rbx,%rax
  3c:	5b                   	pop    %rbx
  3d:	5d                   	pop    %rbp
  3e:	c3                   	ret
  3f:	e8                   	.byte 0xe8


---
This report is generated by a bot. It may contain errors.
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

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#syz undup

Re: [syzbot] [net?] general protection fault in htb_tcf_block

[Victor Nogueira]

[-- Attachment #1: Type: text/plain, Size: 226 bytes --]

On 31/12/2023 08:04, syzbot wrote:
> HEAD commit:    c2b2ee36250d bridge: cfm: fix enum typo in br_cc_ccm_tx_pa..
> git tree:       net-next
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1041287ee80000

#syz test

[-- Attachment #2: 0001-net-sched-We-should-only-add-appropriate-qdiscs-bloc.patch --]
[-- Type: text/x-patch, Size: 2109 bytes --]

From e63340707ce85f8608e3c3ae3cec1340ef17eede Mon Sep 17 00:00:00 2001
From: Victor Nogueira <victor@mojatatu.com>
Date: Thu, 28 Dec 2023 13:18:49 +0000
Subject: [PATCH net-next 1/1] net/sched: We should only add appropriate qdiscs
 blocks to ports' xarray

We should only add qdiscs to the blocks ports' xarray in ingress that
support ingress_block_set/get or in egress that support
egress_block_set/get.

Fixes: 913b47d3424e ("net/sched: Introduce tc block netdev tracking infra")

Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
---
 net/sched/sch_api.c | 34 ++++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 299086bb6205..426be81276f1 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1187,23 +1187,29 @@ static int qdisc_block_add_dev(struct Qdisc *sch, struct net_device *dev,
 	struct tcf_block *block;
 	int err;
 
-	block = cl_ops->tcf_block(sch, TC_H_MIN_INGRESS, NULL);
-	if (block) {
-		err = xa_insert(&block->ports, dev->ifindex, dev, GFP_KERNEL);
-		if (err) {
-			NL_SET_ERR_MSG(extack,
-				       "ingress block dev insert failed");
-			return err;
+	if (sch->ops->ingress_block_get) {
+		block = cl_ops->tcf_block(sch, TC_H_MIN_INGRESS, NULL);
+		if (block) {
+			err = xa_insert(&block->ports, dev->ifindex, dev,
+					GFP_KERNEL);
+			if (err) {
+				NL_SET_ERR_MSG(extack,
+					       "ingress block dev insert failed");
+				return err;
+			}
 		}
 	}
 
-	block = cl_ops->tcf_block(sch, TC_H_MIN_EGRESS, NULL);
-	if (block) {
-		err = xa_insert(&block->ports, dev->ifindex, dev, GFP_KERNEL);
-		if (err) {
-			NL_SET_ERR_MSG(extack,
-				       "Egress block dev insert failed");
-			goto err_out;
+	if (sch->ops->egress_block_get) {
+		block = cl_ops->tcf_block(sch, TC_H_MIN_EGRESS, NULL);
+		if (block) {
+			err = xa_insert(&block->ports, dev->ifindex, dev,
+					GFP_KERNEL);
+			if (err) {
+				NL_SET_ERR_MSG(extack,
+					       "Egress block dev insert failed");
+				goto err_out;
+			}
 		}
 	}
 
-- 
2.25.1

Re: [syzbot] [net?] general protection fault in htb_tcf_block

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+806b0572c8d06b66b234@syzkaller.appspotmail.com

Tested on:

commit:         92de776d Merge tag 'mlx5-updates-2023-12-20' of git://..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=141ab32de80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a4e9ca8e3c104d2a
dashboard link: https://syzkaller.appspot.com/bug?extid=806b0572c8d06b66b234
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=14e64091e80000

Note: testing is done by a robot and is best-effort only.