Hi,
We observed an issue "KASAN: use-after-free Read in tcp_write_timer_handler" during fuzzing.
Unfortunately, we have not found a reproducer for the crash yet. We
will inform you if we have any update on this crash. Detailed crash
information is attached below.
Best regards,
Dae R. Jeong
-----
- Kernel version:
6.0-rc7
- Crash report:
==================================================================
BUG: KASAN: use-after-free in tcp_probe_timer net/ipv4/tcp_timer.c:378 [inline]
BUG: KASAN: use-after-free in tcp_write_timer_handler+0x921/0xa60 net/ipv4/tcp_timer.c:624
Read of size 1 at addr ffff888046bc86a5 by task syz-fuzzer/6625
CPU: 0 PID: 6625 Comm: syz-fuzzer Not tainted 6.0.0-rc7-00167-g92162e4a9862 #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1cf/0x2b7 lib/dump_stack.c:106
print_address_description+0x21/0x470 mm/kasan/report.c:317
print_report+0x108/0x1f0 mm/kasan/report.c:433
kasan_report+0xe5/0x110 mm/kasan/report.c:495
tcp_probe_timer net/ipv4/tcp_timer.c:378 [inline]
tcp_write_timer_handler+0x921/0xa60 net/ipv4/tcp_timer.c:624
tcp_write_timer+0x1a5/0x2c0 net/ipv4/tcp_timer.c:637
call_timer_fn+0xf6/0x220 kernel/time/timer.c:1474
expire_timers kernel/time/timer.c:1519 [inline]
__run_timers+0x76f/0x980 kernel/time/timer.c:1790
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1803
__do_softirq+0x372/0x783 kernel/softirq.c:571
__irq_exit_rcu+0xcf/0x160 kernel/softirq.c:650
irq_exit_rcu+0x5/0x20 kernel/softirq.c:662
sysvec_apic_timer_interrupt+0x43/0xb0 arch/x86/kernel/apic/apic.c:1106
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:649
RIP: 0033:0x421fb1
Code: 90 48 8b 4f 18 90 49 b8 00 00 00 00 00 80 00 00 49 01 c8 49 c1 e8 1a 66 90 49 81 f8 00 00 40 00 0f 83 e2 00 00 00 4a 8b 14 c2 <84> 02 49 89 c8 48 c1 e9 10 81 e1 ff 03 00 00 44 0f b6 8c 0a 00 04
RSP: 002b:00007f3d50bebd38 EFLAGS: 00000287
RAX: 000000c001a0d140 RBX: 000000c001bba000 RCX: 000000c001a0c000
RDX: 00007f3d51bef000 RSI: 000000c000025240 RDI: 00007f3d791daa28
RBP: 00007f3d50bebd78 R08: 0000000000203000 R09: 00007f3d4c2f6001
R10: 000000000000008a R11: 0000000000004048 R12: 0000000000000004
R13: 000000c001a0d140 R14: 000000c000007520 R15: 0000000000000180
</TASK>
Allocated by task 6664:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:437 [inline]
__kasan_slab_alloc+0xa3/0xd0 mm/kasan/common.c:470
kasan_slab_alloc include/linux/kasan.h:224 [inline]
slab_post_alloc_hook mm/slab.h:727 [inline]
slab_alloc_node mm/slub.c:3248 [inline]
slab_alloc mm/slub.c:3256 [inline]
__kmem_cache_alloc_lru mm/slub.c:3263 [inline]
kmem_cache_alloc+0x2e6/0x450 mm/slub.c:3273
kmem_cache_zalloc include/linux/slab.h:723 [inline]
net_alloc net/core/net_namespace.c:404 [inline]
copy_net_ns+0x193/0x6d0 net/core/net_namespace.c:459
create_new_namespaces+0x4db/0xa40 kernel/nsproxy.c:110
unshare_nsproxy_namespaces+0x11e/0x180 kernel/nsproxy.c:226
ksys_unshare+0x5a9/0xbc0 kernel/fork.c:3183
__do_sys_unshare kernel/fork.c:3254 [inline]
__se_sys_unshare kernel/fork.c:3252 [inline]
__x64_sys_unshare+0x34/0x40 kernel/fork.c:3252
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4e/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Freed by task 6874:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track+0x3d/0x60 mm/kasan/common.c:45
kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:370
____kasan_slab_free+0x134/0x1c0 mm/kasan/common.c:367
kasan_slab_free include/linux/kasan.h:200 [inline]
slab_free_hook mm/slub.c:1759 [inline]
slab_free_freelist_hook+0x278/0x370 mm/slub.c:1785
slab_free mm/slub.c:3539 [inline]
kmem_cache_free+0x11a/0x310 mm/slub.c:3556
net_free net/core/net_namespace.c:433 [inline]
cleanup_net+0xd68/0xe20 net/core/net_namespace.c:616
process_one_work+0x83f/0x11a0 kernel/workqueue.c:2289
worker_thread+0xa6c/0x1290 kernel/workqueue.c:2436
kthread+0x28a/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
Last potentially related work creation:
kasan_save_stack+0x2b/0x50 mm/kasan/common.c:38
__kasan_record_aux_stack+0xac/0xc0 mm/kasan/generic.c:348
insert_work+0x54/0x400 kernel/workqueue.c:1358
__queue_work+0xa95/0xe00 kernel/workqueue.c:1517
call_timer_fn+0xf6/0x220 kernel/time/timer.c:1474
expire_timers kernel/time/timer.c:1514 [inline]
__run_timers+0x7a2/0x980 kernel/time/timer.c:1790
__do_softirq+0x372/0x783 kernel/softirq.c:571
Second to last potentially related work creation:
kasan_save_stack+0x2b/0x50 mm/kasan/common.c:38
__kasan_record_aux_stack+0xac/0xc0 mm/kasan/generic.c:348
insert_work+0x54/0x400 kernel/workqueue.c:1358
__queue_work+0xa95/0xe00 kernel/workqueue.c:1517
call_timer_fn+0xf6/0x220 kernel/time/timer.c:1474
expire_timers kernel/time/timer.c:1514 [inline]
__run_timers+0x7a2/0x980 kernel/time/timer.c:1790
__do_softirq+0x372/0x783 kernel/softirq.c:571
The buggy address belongs to the object at ffff888046bc8000
which belongs to the cache net_namespace of size 6784
The buggy address is located 1701 bytes inside of
6784-byte region [ffff888046bc8000, ffff888046bc9a80)
The buggy address belongs to the physical page:
page:ffffea00011af200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x46bc8
head:ffffea00011af200 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888013618f00
raw: 0000000000000000 0000000080040004 00000001ffffffff 0000000000000000
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 6664, tgid 6664 (syz-executor.0), ts 88505587135, free_ts 0
prep_new_page mm/page_alloc.c:2532 [inline]
get_page_from_freelist+0x800/0xc10 mm/page_alloc.c:4283
__alloc_pages+0x2f0/0x650 mm/page_alloc.c:5549
alloc_slab_page mm/slub.c:1829 [inline]
allocate_slab+0x1eb/0xc00 mm/slub.c:1974
new_slab mm/slub.c:2034 [inline]
___slab_alloc+0x581/0xff0 mm/slub.c:3036
__slab_alloc mm/slub.c:3123 [inline]
slab_alloc_node mm/slub.c:3214 [inline]
slab_alloc mm/slub.c:3256 [inline]
__kmem_cache_alloc_lru mm/slub.c:3263 [inline]
kmem_cache_alloc+0x386/0x450 mm/slub.c:3273
kmem_cache_zalloc include/linux/slab.h:723 [inline]
net_alloc net/core/net_namespace.c:404 [inline]
copy_net_ns+0x193/0x6d0 net/core/net_namespace.c:459
create_new_namespaces+0x4db/0xa40 kernel/nsproxy.c:110
unshare_nsproxy_namespaces+0x11e/0x180 kernel/nsproxy.c:226
ksys_unshare+0x5a9/0xbc0 kernel/fork.c:3183
__do_sys_unshare kernel/fork.c:3254 [inline]
__se_sys_unshare kernel/fork.c:3252 [inline]
__x64_sys_unshare+0x34/0x40 kernel/fork.c:3252
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4e/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0xcd
page_owner free stack trace missing
Memory state around the buggy address:
ffff888046bc8580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888046bc8600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888046bc8680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888046bc8700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888046bc8780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
