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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a379972973a8 Merge branch 'net-page_pool-add-netlink-based..
git tree: net-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1421b7ece80000
kernel config: https://syzkaller.appspot.com/x/.config?x=abf6d5a82dab01fe
dashboard link: https://syzkaller.appspot.com/bug?extid=f9f8efb58a4db2ca98d0
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=117d9e64e80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16826ec4e80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fc5f22d6faa1/disk-a3799729.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e535e5c28162/vmlinux-a3799729.xz
kernel image: https://storage.googleapis.com/syzbot-assets/32eefbbcadbb/bzImage-a3799729.xz

The issue was bisected to:

commit 083772c9f972dcc248913b52a0dec1025baa1e16
Author: Jakub Kicinski <ku...@kernel.org>
Date: Sun Nov 26 23:07:30 2023 +0000

net: page_pool: record pools per netdev

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=10c72162e80000
final oops: https://syzkaller.appspot.com/x/report.txt?x=12c72162e80000
console output: https://syzkaller.appspot.com/x/log.txt?x=14c72162e80000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f9f8ef...@syzkaller.appspotmail.com
Fixes: 083772c9f972 ("net: page_pool: record pools per netdev")

Illegal XDP return value 4294946546 on prog (id 2) dev N/A, expect packet loss!
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 5064 Comm: syz-executor391 Not tainted 6.7.0-rc2-syzkaller-00533-ga379972973a8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
RIP: 0010:__hlist_del include/linux/list.h:988 [inline]
RIP: 0010:hlist_del include/linux/list.h:1002 [inline]
RIP: 0010:page_pool_unlist+0xd1/0x170 net/core/page_pool_user.c:342
Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 90 00 00 00 4c 8b a3 f0 06 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 75 68 48 85 ed 49 89 2c 24 74 24 e8 1b ca 07 f9 48 8d
RSP: 0018:ffffc900039ff768 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff88814ae02000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88814ae026f0
RBP: 0000000000000000 R08: 0000000000000000 R09: fffffbfff1d57fdc
R10: ffffffff8eabfee3 R11: ffffffff8aa0008b R12: 0000000000000000
R13: ffff88814ae02000 R14: dffffc0000000000 R15: 0000000000000001
FS: 000055555717a380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000002555398 CR3: 0000000025044000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__page_pool_destroy net/core/page_pool.c:851 [inline]
page_pool_release+0x507/0x6b0 net/core/page_pool.c:891
page_pool_destroy+0x1ac/0x4c0 net/core/page_pool.c:956
xdp_test_run_teardown net/bpf/test_run.c:216 [inline]
bpf_test_run_xdp_live+0x1578/0x1af0 net/bpf/test_run.c:388
bpf_prog_test_run_xdp+0x827/0x1530 net/bpf/test_run.c:1254
bpf_prog_test_run kernel/bpf/syscall.c:4041 [inline]
__sys_bpf+0x11bf/0x4920 kernel/bpf/syscall.c:5402
__do_sys_bpf kernel/bpf/syscall.c:5488 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5486 [inline]
__x64_sys_bpf+0x78/0xc0 kernel/bpf/syscall.c:5486
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f616195a4a9
Code: 48 83 c4 28 c3 e8 37 17 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:00007ffe858ce5c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007ffe858ce798 RCX: 00007f616195a4a9
RDX: 0000000000000048 RSI: 0000000020000340 RDI: 000000000000000a
RBP: 00007f61619cd610 R08: 0000000000000000 R09: 00007ffe858ce798
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffe858ce788 R14: 0000000000000001 R15: 0000000000000001
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__hlist_del include/linux/list.h:988 [inline]
RIP: 0010:hlist_del include/linux/list.h:1002 [inline]
RIP: 0010:page_pool_unlist+0xd1/0x170 net/core/page_pool_user.c:342
Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 90 00 00 00 4c 8b a3 f0 06 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 75 68 48 85 ed 49 89 2c 24 74 24 e8 1b ca 07 f9 48 8d
RSP: 0018:ffffc900039ff768 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff88814ae02000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88814ae026f0
RBP: 0000000000000000 R08: 0000000000000000 R09: fffffbfff1d57fdc
R10: ffffffff8eabfee3 R11: ffffffff8aa0008b R12: 0000000000000000
R13: ffff88814ae02000 R14: dffffc0000000000 R15: 0000000000000001
FS: 000055555717a380(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2640df1b10 CR3: 0000000025044000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: df 48 89 fisttps -0x77(%rax)
3: fa cli
4: 48 c1 ea 03 shr $0x3,%rdx
8: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
c: 0f 85 90 00 00 00 jne 0xa2
12: 4c 8b a3 f0 06 00 00 mov 0x6f0(%rbx),%r12
19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
20: fc ff df
23: 4c 89 e2 mov %r12,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2e: 75 68 jne 0x98
30: 48 85 ed test %rbp,%rbp
33: 49 89 2c 24 mov %rbp,(%r12)
37: 74 24 je 0x5d
39: e8 1b ca 07 f9 call 0xf907ca59
3e: 48 rex.W
3f: 8d .byte 0x8d


---
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 syzk...@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

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.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[Eric Dumazet]

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git
main

```
diff --git a/net/core/page_pool_user.c b/net/core/page_pool_user.c
index 1426434a7e1587797da92f3199c0012559b51271..07becd4eceddcd4be9e5bea6479f8ffd16dac851
100644
--- a/net/core/page_pool_user.c
+++ b/net/core/page_pool_user.c
@@ -339,7 +339,8 @@ void page_pool_unlist(struct page_pool *pool)
mutex_lock(&page_pools_lock);
netdev_nl_page_pool_event(pool, NETDEV_CMD_PAGE_POOL_DEL_NTF);
xa_erase(&page_pools, pool->user.id);
- hlist_del(&pool->user.list);
+ if (!hlist_unhashed(&pool->user.list))
+ hlist_del(&pool->user.list);
mutex_unlock(&page_pools_lock);
}

```

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+f9f8ef...@syzkaller.appspotmail.com

Tested on:

commit: f1be1e04 Merge branch '40GbE' of git://git.kernel.org/..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git main
console output: https://syzkaller.appspot.com/x/log.txt?x=1333cb78e80000

kernel config: https://syzkaller.appspot.com/x/.config?x=abf6d5a82dab01fe
dashboard link: https://syzkaller.appspot.com/bug?extid=f9f8efb58a4db2ca98d0
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=174c37a4e80000

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

[Lizhi Xu]

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git a379972973a8

diff --git a/net/core/page_pool_user.c b/net/core/page_pool_user.c
index 1426434a7e15..ca71f4103b3a 100644

--- a/net/core/page_pool_user.c
+++ b/net/core/page_pool_user.c
@@ -339,7 +339,8 @@ void page_pool_unlist(struct page_pool *pool)
mutex_lock(&page_pools_lock);
netdev_nl_page_pool_event(pool, NETDEV_CMD_PAGE_POOL_DEL_NTF);
xa_erase(&page_pools, pool->user.id);
- hlist_del(&pool->user.list);

+ if (pool->slow.netdev)
+ hlist_del(&pool->user.list);
mutex_unlock(&page_pools_lock);
}

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+f9f8ef...@syzkaller.appspotmail.com

Tested on:

commit: a3799729 Merge branch 'net-page_pool-add-netlink-based..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=127a08bae80000

kernel config: https://syzkaller.appspot.com/x/.config?x=abf6d5a82dab01fe
dashboard link: https://syzkaller.appspot.com/bug?extid=f9f8efb58a4db2ca98d0
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=10c4e3aae80000

[Lizhi Xu]

[Syz report]

[Analysis]
If "user.list" is initialized, the corresponding slow.netdev device must exist,
so before recycling "user.list", it is necessary to confirm that the "slow.netdev"
device is valid.

[Fix]
Add slow.netdev != NULL check before delete "user.list".

Fixes: 083772c9f972 ("net: page_pool: record pools per netdev")

Reported-by: syzbot+f9f8ef...@syzkaller.appspotmail.com
Signed-off-by: Lizhi Xu <lizh...@windriver.com>
---
net/core/page_pool_user.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/core/page_pool_user.c b/net/core/page_pool_user.c
index 1426434a7e15..ca71f4103b3a 100644
--- a/net/core/page_pool_user.c
+++ b/net/core/page_pool_user.c
@@ -339,7 +339,8 @@ void page_pool_unlist(struct page_pool *pool)
mutex_lock(&page_pools_lock);
netdev_nl_page_pool_event(pool, NETDEV_CMD_PAGE_POOL_DEL_NTF);
xa_erase(&page_pools, pool->user.id);
- hlist_del(&pool->user.list);
+ if (pool->slow.netdev)
+ hlist_del(&pool->user.list);
mutex_unlock(&page_pools_lock);
}

--
2.26.1

[Eric Dumazet]

I sent a fix already ?

https://lore.kernel.org/netdev/CANn89i+6BuZA6AjocG_0zTkD1u=pNgZc_DpZMO=yUN=S1c...@mail.gmail.com/

Please do not attribute to yourself work done by others, let me submit
the fix formally, thanks.

[Lizhi Xu]

What exists may not necessarily be right, and how do you prove that I saw your
fix before fixing it?

You have only tested on syzbot, that's all.
This does not mean that others should refer to you for repairs, nor does it
prove that you have made repairs, and others cannot fix them.

Thanks

[Eric Dumazet]

I am just saying I sent a fix already, and that it was sent a few
minutes after the syzbot report was available.

(You included syzbot+f9f8ef...@syzkaller.appspotmail.com in
your report, meaning that you must have seen my patch)

It is not because I sleep during night time that you can decide to use
my work without any credits.