Message-ID: <685d9eb1.050a0220.2303ee.02a7.GAE@google.com>
Date: Thu, 26 Jun 2025 12:25:37 -0700
From: syzbot <syzbot+430f9f76633641a62217@...kaller.appspotmail.com>
To: andrew@...n.ch, danieller@...dia.com, davem@...emloft.net, 
	edumazet@...gle.com, horms@...nel.org, kory.maincent@...tlin.com, 
	kuba@...nel.org, linux-kernel@...r.kernel.org, maxime.chevallier@...tlin.com, 
	netdev@...r.kernel.org, pabeni@...hat.com, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [net?] KASAN: slab-out-of-bounds Read in pause_parse_request

Hello,

syzbot found the following issue on:

HEAD commit:    a9b24b3583ae net: phy: realtek: add error handling to rtl8..
git tree:       net-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=15d50f0c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fab0bcec5be1995b
dashboard link: https://syzkaller.appspot.com/bug?extid=430f9f76633641a62217
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17d1b182580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=120bff0c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9205e4571dc2/disk-a9b24b35.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9a698a98f3a1/vmlinux-a9b24b35.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5964c8e14f44/bzImage-a9b24b35.xz

The issue was bisected to:

commit 963781bdfe2007e062e05b6b8a263ae9340bd523
Author: Jakub Kicinski <kuba@...nel.org>
Date:   Mon Jun 23 23:17:15 2025 +0000

    net: ethtool: call .parse_request for SET handlers

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=101f208c580000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=121f208c580000
console output: https://syzkaller.appspot.com/x/log.txt?x=141f208c580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+430f9f76633641a62217@...kaller.appspotmail.com
Fixes: 963781bdfe20 ("net: ethtool: call .parse_request for SET handlers")

==================================================================
BUG: KASAN: slab-out-of-bounds in pause_parse_request+0x40/0x160 net/ethtool/pause.c:37
Read of size 8 at addr ffff888034301530 by task syz-executor369/5848

CPU: 1 UID: 0 PID: 5848 Comm: syz-executor369 Not tainted 6.16.0-rc2-syzkaller-00867-ga9b24b3583ae #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xd2/0x2b0 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 pause_parse_request+0x40/0x160 net/ethtool/pause.c:37
 ethnl_default_parse net/ethtool/netlink.c:456 [inline]
 ethnl_default_set_doit+0x2c1/0xa40 net/ethtool/netlink.c:881
 genl_family_rcv_msg_doit+0x215/0x300 net/netlink/genetlink.c:1115
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x205/0x470 net/netlink/af_netlink.c:2534
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x758/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:729
 ____sys_sendmsg+0x505/0x830 net/socket.c:2614
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668
 __sys_sendmsg net/socket.c:2700 [inline]
 __do_sys_sendmsg net/socket.c:2705 [inline]
 __se_sys_sendmsg net/socket.c:2703 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2703
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f99cc8969d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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:00007ffdf8e93908 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f99cc8e44ad RCX: 00007f99cc8969d9
RDX: 0000000000000040 RSI: 0000200000000000 RDI: 0000000000000003
RBP: 00007f99cc8e447d R08: 0000000000000000 R09: 0000555500000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f99cc8e43e5
R13: 0000000000000001 R14: 00007ffdf8e93950 R15: 0000000000000003
 </TASK>

Allocated by task 5848:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4328 [inline]
 __kmalloc_noprof+0x27a/0x4f0 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 kmalloc_array_noprof include/linux/slab.h:948 [inline]
 genl_family_rcv_msg_attrs_parse+0xa3/0x2a0 net/netlink/genetlink.c:940
 genl_family_rcv_msg_doit+0xb8/0x300 net/netlink/genetlink.c:1093
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x205/0x470 net/netlink/af_netlink.c:2534
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x758/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:729
 ____sys_sendmsg+0x505/0x830 net/socket.c:2614
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668
 __sys_sendmsg net/socket.c:2700 [inline]
 __do_sys_sendmsg net/socket.c:2705 [inline]
 __se_sys_sendmsg net/socket.c:2703 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2703
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888034301500
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 8 bytes to the right of
 allocated 40-byte region [ffff888034301500, ffff888034301528)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x34301
ksm flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801a4418c0 ffffea00009e8e40 dead000000000003
raw: 0000000000000000 0000000080200020 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 1153, tgid 1153 (kworker/u8:6), ts 27371323863, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
 alloc_slab_page mm/slub.c:2451 [inline]
 allocate_slab+0x8a/0x3b0 mm/slub.c:2619
 new_slab mm/slub.c:2673 [inline]
 ___slab_alloc+0xbfc/0x1480 mm/slub.c:3859
 __slab_alloc mm/slub.c:3949 [inline]
 __slab_alloc_node mm/slub.c:4024 [inline]
 slab_alloc_node mm/slub.c:4185 [inline]
 __do_kmalloc_node mm/slub.c:4327 [inline]
 __kmalloc_noprof+0x305/0x4f0 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 lsm_blob_alloc security/security.c:684 [inline]
 lsm_task_alloc security/security.c:771 [inline]
 security_task_alloc+0x4d/0x360 security/security.c:3160
 copy_process+0x1530/0x3c00 kernel/fork.c:2151
 kernel_clone+0x21e/0x870 kernel/fork.c:2599
 user_mode_thread+0xdd/0x140 kernel/fork.c:2677
 call_usermodehelper_exec_work+0x5c/0x230 kernel/umh.c:171
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888034301400: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888034301480: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888034301500: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
                                     ^
 ffff888034301580: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888034301600: 00 00 00 00 00 00 05 fc fc fc fc fc fc fc fc fc
==================================================================


---
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