[v5.15] KASAN: use-after-free Read in tcp_retransmit_timer

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syzbot

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Mar 20, 2023, 12:46:54 PM3/20/23
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Hello,

syzbot found the following issue on:

HEAD commit: 8020ae3c051d Linux 5.15.103
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1679cc91c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=d4215fb4040f8f8d
dashboard link: https://syzkaller.appspot.com/bug?extid=723f5bcd5b45c77efb39
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b1c6db1e6932/disk-8020ae3c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1285a5761f65/vmlinux-8020ae3c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e5d44eff1e6b/bzImage-8020ae3c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+723f5b...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in tcp_retransmit_timer+0x6ee/0x2890 net/ipv4/tcp_timer.c:515
Read of size 8 at addr ffff888023121c98 by task swapper/1/0

CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.15.103-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
print_address_description+0x63/0x3b0 mm/kasan/report.c:248
__kasan_report mm/kasan/report.c:434 [inline]
kasan_report+0x16b/0x1c0 mm/kasan/report.c:451
tcp_retransmit_timer+0x6ee/0x2890 net/ipv4/tcp_timer.c:515
tcp_write_timer_handler+0x1f7/0x9c0 net/ipv4/tcp_timer.c:626
tcp_write_timer+0x12e/0x280 net/ipv4/tcp_timer.c:646
call_timer_fn+0x1d7/0x6f0 kernel/time/timer.c:1421
expire_timers kernel/time/timer.c:1466 [inline]
__run_timers+0x67c/0x890 kernel/time/timer.c:1737
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1750
__do_softirq+0x3da/0xa10 kernel/softirq.c:558
invoke_softirq kernel/softirq.c:432 [inline]
__irq_exit_rcu+0x155/0x240 kernel/softirq.c:636
irq_exit_rcu+0x5/0x20 kernel/softirq.c:648
sysvec_apic_timer_interrupt+0x91/0xb0 arch/x86/kernel/apic/apic.c:1097
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:22 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:132 [inline]
RIP: 0010:acpi_safe_halt drivers/acpi/processor_idle.c:110 [inline]
RIP: 0010:acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:570
Code: 57 54 f7 48 83 e3 08 0f 85 0a 01 00 00 4c 8d 74 24 20 e8 b4 c2 5a f7 0f 1f 44 00 00 e8 1a 53 54 f7 0f 00 2d 03 92 b6 00 fb f4 <4c> 89 f3 48 c1 eb 03 42 80 3c 3b 00 74 08 4c 89 f7 e8 eb dc 9d f7
RSP: 0018:ffffc90000d67b00 EFLAGS: 000002d3
RAX: ffffffff8a2c25b6 RBX: 0000000000000000 RCX: ffff888012998000
RDX: 0000000000000000 RSI: ffffffff8a8afc80 RDI: ffffffff8ad8b940
RBP: ffffc90000d67b90 R08: ffffffff8186e890 R09: ffffed1002533001
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff920001acf60
R13: ffff888018b15804 R14: ffffc90000d67b20 R15: dffffc0000000000
acpi_idle_enter+0x352/0x4f0 drivers/acpi/processor_idle.c:705
cpuidle_enter_state+0x521/0xef0 drivers/cpuidle/cpuidle.c:237
cpuidle_enter+0x59/0x90 drivers/cpuidle/cpuidle.c:351
call_cpuidle kernel/sched/idle.c:158 [inline]
cpuidle_idle_call kernel/sched/idle.c:239 [inline]
do_idle+0x3e4/0x670 kernel/sched/idle.c:306
cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:403
start_secondary+0x371/0x500 arch/x86/kernel/smpboot.c:270
secondary_startup_64_no_verify+0xb1/0xbb
</TASK>

Allocated by task 3614:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:434 [inline]
__kasan_slab_alloc+0x8e/0xc0 mm/kasan/common.c:467
kasan_slab_alloc include/linux/kasan.h:254 [inline]
slab_post_alloc_hook+0x53/0x380 mm/slab.h:519
slab_alloc_node mm/slub.c:3220 [inline]
slab_alloc mm/slub.c:3228 [inline]
kmem_cache_alloc+0xf3/0x2e0 mm/slub.c:3233
kmem_cache_zalloc include/linux/slab.h:711 [inline]
net_alloc net/core/net_namespace.c:405 [inline]
copy_net_ns+0x143/0x5d0 net/core/net_namespace.c:460
create_new_namespaces+0x425/0x7a0 kernel/nsproxy.c:110
unshare_nsproxy_namespaces+0x11e/0x170 kernel/nsproxy.c:226
ksys_unshare+0x580/0xb20 kernel/fork.c:3094
__do_sys_unshare kernel/fork.c:3168 [inline]
__se_sys_unshare kernel/fork.c:3166 [inline]
__x64_sys_unshare+0x34/0x40 kernel/fork.c:3166
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 1119:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track+0x4b/0x80 mm/kasan/common.c:46
kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
____kasan_slab_free+0xd8/0x120 mm/kasan/common.c:366
kasan_slab_free include/linux/kasan.h:230 [inline]
slab_free_hook mm/slub.c:1705 [inline]
slab_free_freelist_hook+0xdd/0x160 mm/slub.c:1731
slab_free mm/slub.c:3499 [inline]
kmem_cache_free+0x91/0x260 mm/slub.c:3515
net_free net/core/net_namespace.c:434 [inline]
cleanup_net+0xab5/0xb60 net/core/net_namespace.c:617
process_one_work+0x90d/0x1270 kernel/workqueue.c:2306
worker_thread+0xaca/0x1280 kernel/workqueue.c:2453
kthread+0x3f6/0x4f0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

The buggy address belongs to the object at ffff888023121a40
which belongs to the cache net_namespace of size 6464
The buggy address is located 600 bytes inside of
6464-byte region [ffff888023121a40, ffff888023123380)
The buggy address belongs to the page:
page:ffffea00008c4800 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888023123480 pfn:0x23120
head:ffffea00008c4800 order:3 compound_mapcount:0 compound_pincount:0
memcg:ffff88801a221841
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffffea0001cc7600 0000000200000002 ffff888011dc63c0
raw: ffff888023123480 0000000080040002 00000001ffffffff ffff88801a221841
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 3609, ts 69361386776, free_ts 65956853790
prep_new_page mm/page_alloc.c:2426 [inline]
get_page_from_freelist+0x32dd/0x3470 mm/page_alloc.c:4159
__alloc_pages+0x272/0x790 mm/page_alloc.c:5421
alloc_slab_page mm/slub.c:1775 [inline]
allocate_slab mm/slub.c:1912 [inline]
new_slab+0xbb/0x4b0 mm/slub.c:1975
___slab_alloc+0x6f6/0xe10 mm/slub.c:3008
__slab_alloc mm/slub.c:3095 [inline]
slab_alloc_node mm/slub.c:3186 [inline]
slab_alloc mm/slub.c:3228 [inline]
kmem_cache_alloc+0x1e1/0x2e0 mm/slub.c:3233
kmem_cache_zalloc include/linux/slab.h:711 [inline]
net_alloc net/core/net_namespace.c:405 [inline]
copy_net_ns+0x143/0x5d0 net/core/net_namespace.c:460
create_new_namespaces+0x425/0x7a0 kernel/nsproxy.c:110
unshare_nsproxy_namespaces+0x11e/0x170 kernel/nsproxy.c:226
ksys_unshare+0x580/0xb20 kernel/fork.c:3094
__do_sys_unshare kernel/fork.c:3168 [inline]
__se_sys_unshare kernel/fork.c:3166 [inline]
__x64_sys_unshare+0x34/0x40 kernel/fork.c:3166
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1340 [inline]
free_pcp_prepare mm/page_alloc.c:1391 [inline]
free_unref_page_prepare+0xcb7/0xd70 mm/page_alloc.c:3317
free_unref_page+0x95/0x2d0 mm/page_alloc.c:3396
do_slab_free mm/slub.c:3487 [inline]
___cache_free+0xe3/0x100 mm/slub.c:3506
qlist_free_all+0x36/0x90 mm/kasan/quarantine.c:176
kasan_quarantine_reduce+0x162/0x180 mm/kasan/quarantine.c:283
__kasan_slab_alloc+0x2f/0xc0 mm/kasan/common.c:444
kasan_slab_alloc include/linux/kasan.h:254 [inline]
slab_post_alloc_hook+0x53/0x380 mm/slab.h:519
slab_alloc_node mm/slub.c:3220 [inline]
kmem_cache_alloc_node+0x121/0x320 mm/slub.c:3256
__alloc_skb+0xdd/0x590 net/core/skbuff.c:415
alloc_skb_fclone include/linux/skbuff.h:1216 [inline]
sk_stream_alloc_skb+0x1fc/0xad0 net/ipv4/tcp.c:885
tcp_sendmsg_locked+0xe0c/0x3ab0 net/ipv4/tcp.c:1308
tcp_sendmsg+0x2c/0x40 net/ipv4/tcp.c:1460
sock_sendmsg_nosec net/socket.c:704 [inline]
sock_sendmsg net/socket.c:724 [inline]
sock_write_iter+0x39b/0x530 net/socket.c:1060
call_write_iter include/linux/fs.h:2103 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0xacf/0xe50 fs/read_write.c:594
ksys_write+0x1a2/0x2c0 fs/read_write.c:647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80

Memory state around the buggy address:
ffff888023121b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888023121c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888023121c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888023121d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888023121d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: 57 push %rdi
1: 54 push %rsp
2: f7 48 83 e3 08 0f 85 testl $0x850f08e3,-0x7d(%rax)
9: 0a 01 or (%rcx),%al
b: 00 00 add %al,(%rax)
d: 4c 8d 74 24 20 lea 0x20(%rsp),%r14
12: e8 b4 c2 5a f7 callq 0xf75ac2cb
17: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
1c: e8 1a 53 54 f7 callq 0xf754533b
21: 0f 00 2d 03 92 b6 00 verw 0xb69203(%rip) # 0xb6922b
28: fb sti
29: f4 hlt
* 2a: 4c 89 f3 mov %r14,%rbx <-- trapping instruction
2d: 48 c1 eb 03 shr $0x3,%rbx
31: 42 80 3c 3b 00 cmpb $0x0,(%rbx,%r15,1)
36: 74 08 je 0x40
38: 4c 89 f7 mov %r14,%rdi
3b: e8 eb dc 9d f7 callq 0xf79ddd2b


---
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syzbot

unread,
Sep 13, 2023, 10:10:47 PM9/13/23
to syzkaller...@googlegroups.com
Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.
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