Message-ID: <6876cc3c.a00a0220.3af5df.000a.GAE@google.com>
Date: Tue, 15 Jul 2025 14:46:36 -0700
From: syzbot <syzbot+9d2a6ef56c3805144bf0@...kaller.appspotmail.com>
To: davem@...emloft.net, dsahern@...nel.org, edumazet@...gle.com, 
	horms@...nel.org, kuba@...nel.org, kuniyu@...gle.com, 
	linux-kernel@...r.kernel.org, ncardwell@...gle.com, netdev@...r.kernel.org, 
	pabeni@...hat.com, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [net?] KASAN: slab-use-after-free Read in tcp_prune_ofo_queue

Hello,

syzbot found the following issue on:

HEAD commit:    55e8757c6962 Merge branch 'net-mctp-improved-bind-handling'
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15834382580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f8235fb7e74dd7f6
dashboard link: https://syzkaller.appspot.com/bug?extid=9d2a6ef56c3805144bf0
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1445058c580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=148e098c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6c4b54c5d7b6/disk-55e8757c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3885c5b76f45/vmlinux-55e8757c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f16a3c7b11be/bzImage-55e8757c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9d2a6ef56c3805144bf0@...kaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in tcp_can_ingest net/ipv4/tcp_input.c:4896 [inline]
BUG: KASAN: slab-use-after-free in tcp_prune_ofo_queue+0x37e/0x6e0 net/ipv4/tcp_input.c:5520
Read of size 4 at addr ffff88802779f350 by task syz.2.45/6135

CPU: 1 UID: 0 PID: 6135 Comm: syz.2.45 Not tainted 6.16.0-rc5-syzkaller-01444-g55e8757c6962 #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
 tcp_can_ingest net/ipv4/tcp_input.c:4896 [inline]
 tcp_prune_ofo_queue+0x37e/0x6e0 net/ipv4/tcp_input.c:5520
 tcp_prune_queue net/ipv4/tcp_input.c:5575 [inline]
 tcp_try_rmem_schedule+0xb6b/0x1830 net/ipv4/tcp_input.c:4907
 tcp_data_queue+0x4e3/0x6380 net/ipv4/tcp_input.c:5192
 tcp_rcv_established+0xf9e/0x1eb0 net/ipv4/tcp_input.c:6208
 tcp_v4_do_rcv+0xa23/0xce0 net/ipv4/tcp_ipv4.c:1925
 sk_backlog_rcv include/net/sock.h:1148 [inline]
 __release_sock+0x21c/0x350 net/core/sock.c:3188
 release_sock+0x5f/0x1f0 net/core/sock.c:3742
 tcp_sendmsg+0x39/0x50 net/ipv4/tcp.c:1394
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg+0x19c/0x270 net/socket.c:729
 __sys_sendto+0x3bd/0x520 net/socket.c:2228
 __do_sys_sendto net/socket.c:2235 [inline]
 __se_sys_sendto net/socket.c:2231 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2231
 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: 0033:0x7fa36638e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdf475f108 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007fa3665b5fa0 RCX: 00007fa36638e929
RDX: 000000000000059a RSI: 0000200000000580 RDI: 0000000000000003
RBP: 00007fa366410b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000010008095 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa3665b5fa0 R14: 00007fa3665b5fa0 R15: 0000000000000006
 </TASK>

Allocated by task 6135:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 unpoison_slab_object mm/kasan/common.c:319 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:345
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4148 [inline]
 slab_alloc_node mm/slub.c:4197 [inline]
 kmem_cache_alloc_node_noprof+0x1bb/0x3c0 mm/slub.c:4249
 __alloc_skb+0x112/0x2d0 net/core/skbuff.c:659
 alloc_skb_fclone include/linux/skbuff.h:1386 [inline]
 tcp_stream_alloc_skb+0x3d/0x340 net/ipv4/tcp.c:892
 tso_fragment net/ipv4/tcp_output.c:2174 [inline]
 tcp_write_xmit+0xeec/0x67f0 net/ipv4/tcp_output.c:2819
 __tcp_push_pending_frames+0x97/0x360 net/ipv4/tcp_output.c:3016
 tcp_sendmsg_locked+0x483c/0x56d0 net/ipv4/tcp.c:1356
 tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1393
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg+0x19c/0x270 net/socket.c:729
 __sys_sendto+0x3bd/0x520 net/socket.c:2228
 __do_sys_sendto net/socket.c:2235 [inline]
 __se_sys_sendto net/socket.c:2231 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2231
 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

Freed by task 6135:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x62/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2381 [inline]
 slab_free mm/slub.c:4643 [inline]
 kmem_cache_free+0x18f/0x400 mm/slub.c:4745
 tcp_prune_ofo_queue+0x198/0x6e0 net/ipv4/tcp_input.c:5517
 tcp_prune_queue net/ipv4/tcp_input.c:5575 [inline]
 tcp_try_rmem_schedule+0xb6b/0x1830 net/ipv4/tcp_input.c:4907
 tcp_data_queue+0x4e3/0x6380 net/ipv4/tcp_input.c:5192
 tcp_rcv_established+0xf9e/0x1eb0 net/ipv4/tcp_input.c:6208
 tcp_v4_do_rcv+0xa23/0xce0 net/ipv4/tcp_ipv4.c:1925
 sk_backlog_rcv include/net/sock.h:1148 [inline]
 __release_sock+0x21c/0x350 net/core/sock.c:3188
 release_sock+0x5f/0x1f0 net/core/sock.c:3742
 tcp_sendmsg+0x39/0x50 net/ipv4/tcp.c:1394
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg+0x19c/0x270 net/socket.c:729
 __sys_sendto+0x3bd/0x520 net/socket.c:2228
 __do_sys_sendto net/socket.c:2235 [inline]
 __se_sys_sendto net/socket.c:2231 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2231
 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 ffff88802779f180
 which belongs to the cache skbuff_fclone_cache of size 488
The buggy address is located 464 bytes inside of
 freed 488-byte region [ffff88802779f180, ffff88802779f368)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2779e
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff8881416b9a00 dead000000000122 0000000000000000
raw: 0000000000000000 00000000000c000c 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff8881416b9a00 dead000000000122 0000000000000000
head: 0000000000000000 00000000000c000c 00000000f5000000 0000000000000000
head: 00fff00000000001 ffffea00009de781 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6135, tgid 6135 (syz.2.45), ts 109281901479, free_ts 109187086002
 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]
 kmem_cache_alloc_node_noprof+0x280/0x3c0 mm/slub.c:4249
 __alloc_skb+0x112/0x2d0 net/core/skbuff.c:659
 alloc_skb_fclone include/linux/skbuff.h:1386 [inline]
 tcp_stream_alloc_skb+0x3d/0x340 net/ipv4/tcp.c:892
 tcp_sendmsg_locked+0xefc/0x56d0 net/ipv4/tcp.c:1198
 tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1393
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg+0x19c/0x270 net/socket.c:729
 __sys_sendto+0x3bd/0x520 net/socket.c:2228
 __do_sys_sendto net/socket.c:2235 [inline]
 __se_sys_sendto net/socket.c:2231 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2231
 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
page last free pid 5216 tgid 5216 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 __free_frozen_pages+0xc71/0xe70 mm/page_alloc.c:2706
 __slab_free+0x326/0x400 mm/slub.c:4554
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4148 [inline]
 slab_alloc_node mm/slub.c:4197 [inline]
 kmem_cache_alloc_noprof+0x1c1/0x3c0 mm/slub.c:4204
 getname_flags+0xb8/0x540 fs/namei.c:146
 do_readlinkat+0xbc/0x500 fs/stat.c:575
 __do_sys_readlink fs/stat.c:613 [inline]
 __se_sys_readlink fs/stat.c:610 [inline]
 __x64_sys_readlink+0x7f/0x90 fs/stat.c:610
 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

Memory state around the buggy address:
 ffff88802779f200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802779f280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802779f300: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
                                                 ^
 ffff88802779f380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88802779f400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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If the report is already addressed, let syzbot know by replying with:
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