linux-kernel - Re: [syzbot] [mm?] [usb?] WARNING in __alloc

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Message-ID: <68cf09df.050a0220.13cd81.0022.GAE@google.com>
Date: Sat, 20 Sep 2025 13:09:03 -0700
From: syzbot <syzbot+5a2250fd91b28106c37b@...kaller.appspotmail.com>
To: kriish.sharma2006@...il.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [mm?] [usb?] WARNING in __alloc_skb (4)

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in __alloc_skb

------------[ cut here ]------------
kmalloc_reserve: request size 4294965248 exceeds KMALLOC_MAX_SIZE (4194304)
WARNING: net/core/skbuff.c:598 at kmalloc_reserve+0x2df/0x2f0 net/core/skbuff.c:596, CPU#1: dhcpcd/5527
Modules linked in:
CPU: 1 UID: 0 PID: 5527 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:kmalloc_reserve+0x2df/0x2f0 net/core/skbuff.c:596
Code: ff e8 b5 75 54 f8 c6 05 18 35 63 06 01 90 b9 00 00 40 00 48 c7 c7 60 2e b4 8c 48 c7 c6 d4 5d c3 8d 4c 89 ea e8 22 e7 17 f8 90 <0f> 0b 90 90 45 31 e4 e9 37 ff ff ff 0f 1f 44 00 00 90 90 90 90 90
RSP: 0018:ffffc90000a089b0 EFLAGS: 00010246
RAX: 40535143de383200 RBX: dffffc0000000001 RCX: ffff88802f97bc80
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000002
RBP: ffffc90000a089fc R08: ffff8880b8724293 R09: 1ffff110170e4852
R10: dffffc0000000000 R11: ffffed10170e4853 R12: 00000000fffff6c0
R13: 00000000fffff800 R14: 0000000000020820 R15: 1ffff9200014113f
FS:  00007fc29b83c740(0000) GS:ffff8881258a2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc1fdb0168 CR3: 0000000033cd0000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 __alloc_skb+0x142/0x2d0 net/core/skbuff.c:677
 __netdev_alloc_skb+0x108/0x970 net/core/skbuff.c:741
 rx_submit+0x100/0xab0 drivers/net/usb/usbnet.c:-1
 rx_alloc_submit+0xa6/0x140 drivers/net/usb/usbnet.c:1538
 usbnet_bh+0x9a5/0xd70 drivers/net/usb/usbnet.c:1607
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 bh_worker+0x2b1/0x600 kernel/workqueue.c:3607
 tasklet_action+0xc/0x70 kernel/softirq.c:952
 handle_softirqs+0x286/0x870 kernel/softirq.c:622
 do_softirq+0xec/0x180 kernel/softirq.c:523
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x17d/0x1c0 kernel/softirq.c:450
 __dev_open+0x694/0x880 net/core/dev.c:1690
 __dev_change_flags+0x1ea/0x6d0 net/core/dev.c:9630
 netif_change_flags+0x88/0x1a0 net/core/dev.c:9693
 dev_change_flags+0x130/0x260 net/core/dev_api.c:68
 devinet_ioctl+0xbb4/0x1b50 net/ipv4/devinet.c:1199
 inet_ioctl+0x3c0/0x4c0 net/ipv4/af_inet.c:1003
 sock_do_ioctl+0xdc/0x300 net/socket.c:1241
 sock_ioctl+0x576/0x790 net/socket.c:1362
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc29b93c378
Code: 00 00 48 8d 44 24 08 48 89 54 24 e0 48 89 44 24 c0 48 8d 44 24 d0 48 89 44 24 c8 b8 10 00 00 00 c7 44 24 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 07 89 d0 c3 0f 1f 40 00 48 8b 15 49 3a 0d
RSP: 002b:00007ffd8c8eaa48 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000016 RCX: 00007fc29b93c378
RDX: 00007ffd8c8fac40 RSI: 0000000000008914 RDI: 0000000000000016
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd8c90ade0
R13: 00007fc29b83c6c8 R14: 0000000000000028 R15: 0000000000008914
 </TASK>


Tested on:

commit:         846bd222 Add linux-next specific files for 20250919
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16561534580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=135377594f35b576
dashboard link: https://syzkaller.appspot.com/bug?extid=5a2250fd91b28106c37b
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=144b60e2580000