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BUG: KASAN: slab-out-of-bounds in tcp_retransmit_timer+0x2d4c/0x3240 net/ipv4/tcp_timer.c:500
Read of size 8 at addr ffff888065306390 by task syz-fuzzer/6802

CPU: 1 PID: 6802 Comm: syz-fuzzer Not tainted 5.8.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 tcp_retransmit_timer+0x2d4c/0x3240 net/ipv4/tcp_timer.c:500
 tcp_write_timer_handler+0x79b/0xa60 net/ipv4/tcp_timer.c:611
 tcp_write_timer+0xa2/0x2b0 net/ipv4/tcp_timer.c:631
 call_timer_fn+0x1ac/0x760 kernel/time/timer.c:1404
 expire_timers kernel/time/timer.c:1449 [inline]
 __run_timers.part.0+0x54c/0xa20 kernel/time/timer.c:1773
 __run_timers kernel/time/timer.c:1745 [inline]
 run_timer_softirq+0xae/0x1a0 kernel/time/timer.c:1786
 __do_softirq+0x34c/0xa60 kernel/softirq.c:292
 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711
 </IRQ>
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
 do_softirq_own_stack+0x111/0x170 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:387 [inline]
 __irq_exit_rcu kernel/softirq.c:417 [inline]
 irq_exit_rcu+0x229/0x270 kernel/softirq.c:429
 sysvec_apic_timer_interrupt+0x12d/0x220 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:596
RIP: 0033:0x4f56eb
Code: Bad RIP value.
RSP: 002b:000000c002e118a8 EFLAGS: 00000287
RAX: 000000000001a442 RBX: 2faa76ab4da74e47 RCX: 000000000000305a
RDX: 0000000000000c9a RSI: 00000000000000a9 RDI: 000000c00a1cca50
RBP: 000000c002e118c0 R08: 0000000000884160 R09: 0000000000000001
R10: 000000c00b11a000 R11: 000000000000189b R12: 000000000000000e
R13: 00aaaaaaaaaaaaaa R14: 0000000000adc669 R15: 0000000000000038

Allocated by task 3883:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
 slab_post_alloc_hook mm/slab.h:586 [inline]
 slab_alloc mm/slab.c:3320 [inline]
 kmem_cache_alloc+0x12c/0x3b0 mm/slab.c:3484
 getname_flags.part.0+0x50/0x4f0 fs/namei.c:138
 getname_flags fs/namei.c:2646 [inline]
 user_path_at_empty+0xa1/0x100 fs/namei.c:2646
 user_path_at include/linux/namei.h:59 [inline]
 do_faccessat+0x129/0x820 fs/open.c:423
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 3883:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 kasan_set_free_info mm/kasan/common.c:316 [inline]
 __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455
 __cache_free mm/slab.c:3426 [inline]
 kmem_cache_free+0x7f/0x310 mm/slab.c:3694
 putname+0xe1/0x120 fs/namei.c:259
 filename_lookup+0x3b1/0x560 fs/namei.c:2376
 user_path_at include/linux/namei.h:59 [inline]
 do_faccessat+0x129/0x820 fs/open.c:423
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff888065306800
 which belongs to the cache names_cache of size 4096
The buggy address is located 1136 bytes to the left of
 4096-byte region [ffff888065306800, ffff888065307800)
The buggy address belongs to the page:
page:ffffea000194c180 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea000194c180 order:1 compound_mapcount:0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea0001771688 ffffea0001539108 ffff8880aa1d0000
raw: 0000000000000000 ffff888065306800 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888065306280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888065306300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888065306380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                         ^
 ffff888065306400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888065306480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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