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BUG: KASAN: slab-out-of-bounds in tcp_retransmit_timer+0x2c51/0x30e0 net/ipv4/tcp_timer.c:500
Read of size 8 at addr ffff888090824478 by task syz-executor.2/19640

CPU: 1 PID: 19640 Comm: syz-executor.2 Not tainted 5.6.0-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+0x197/0x210 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:641
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
 tcp_retransmit_timer+0x2c51/0x30e0 net/ipv4/tcp_timer.c:500
 tcp_write_timer_handler+0x6be/0x8d0 net/ipv4/tcp_timer.c:611
 tcp_write_timer+0xac/0x2e0 net/ipv4/tcp_timer.c:631
 call_timer_fn+0x1ac/0x780 kernel/time/timer.c:1404
 expire_timers kernel/time/timer.c:1449 [inline]
 __run_timers kernel/time/timer.c:1773 [inline]
 __run_timers kernel/time/timer.c:1740 [inline]
 run_timer_softirq+0x6c3/0x1790 kernel/time/timer.c:1786
 __do_softirq+0x262/0x98c kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x19b/0x1e0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:546 [inline]
 smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1146
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:__sanitizer_cov_trace_pc+0x1a/0x50 kernel/kcov.c:183
Code: c3 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 65 48 8b 04 25 c0 1e 02 00 65 8b 15 b4 96 8c 7e 81 e2 00 01 1f 00 <48> 8b 75 08 75 2b 8b 90 80 13 00 00 83 fa 02 75 20 48 8b 88 88 13
RSP: 0018:ffffc900057f74c8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffff8880557aa480 RBX: 0000000000000002 RCX: 0000000000000007
RDX: 0000000000000000 RSI: ffffffff81febb00 RDI: ffff888214a4a070
RBP: ffffc900057f74c8 R08: ffff8880557aa480 R09: 0000000000000000
R10: ffffed1012d72836 R11: ffff888096b941b3 R12: ffff888214a4a000
R13: ffff888219aed738 R14: 0000000000000002 R15: ffff888214a48000
 ext4_get_group_desc+0x14b/0x2c0 fs/ext4/balloc.c:291
 recently_deleted fs/ext4/ialloc.c:676 [inline]
 find_inode_bit.isra.0+0x194/0x520 fs/ext4/ialloc.c:720
 __ext4_new_inode+0x16eb/0x4fa0 fs/ext4/ialloc.c:912
 ext4_create+0x38a/0x520 fs/ext4/namei.c:2613
 lookup_open+0x12d5/0x1a90 fs/namei.c:3309
 do_last fs/namei.c:3401 [inline]
 path_openat+0xf2c/0x3490 fs/namei.c:3607
 do_filp_open+0x192/0x260 fs/namei.c:3637
 do_sys_openat2+0x5eb/0x7e0 fs/open.c:1149
 do_sys_open+0xf2/0x180 fs/open.c:1165
 __do_sys_openat fs/open.c:1179 [inline]
 __se_sys_openat fs/open.c:1174 [inline]
 __x64_sys_openat+0x9d/0x100 fs/open.c:1174
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c429
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f033f96ec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f033f96f6d4 RCX: 000000000045c429
RDX: 00000000000026e1 RSI: 0000000020000200 RDI: ffffffffffffff9c
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000078d R14: 00000000004c9fc8 R15: 000000000076bf2c

Allocated by task 17389:
 save_stack+0x23/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc mm/kasan/common.c:515 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:488
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:523
 slab_post_alloc_hook mm/slab.h:584 [inline]
 slab_alloc mm/slab.c:3320 [inline]
 kmem_cache_alloc+0x121/0x710 mm/slab.c:3484
 getname_flags fs/namei.c:138 [inline]
 getname_flags+0xd6/0x5b0 fs/namei.c:128
 user_path_at_empty+0x2f/0x50 fs/namei.c:2746
 do_readlinkat+0xe9/0x320 fs/stat.c:409
 __do_sys_readlink fs/stat.c:442 [inline]
 __se_sys_readlink fs/stat.c:439 [inline]
 __x64_sys_readlink+0x78/0xb0 fs/stat.c:439
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 17389:
 save_stack+0x23/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 kasan_set_free_info mm/kasan/common.c:337 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:476
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:485
 __cache_free mm/slab.c:3426 [inline]
 kmem_cache_free+0x86/0x320 mm/slab.c:3694
 putname+0xef/0x130 fs/namei.c:259
 filename_lookup+0x282/0x3e0 fs/namei.c:2475
 user_path_at_empty+0x43/0x50 fs/namei.c:2746
 do_readlinkat+0xe9/0x320 fs/stat.c:409
 __do_sys_readlink fs/stat.c:442 [inline]
 __se_sys_readlink fs/stat.c:439 [inline]
 __x64_sys_readlink+0x78/0xb0 fs/stat.c:439
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888090824b80
 which belongs to the cache names_cache of size 4096
The buggy address is located 1800 bytes to the left of
 4096-byte region [ffff888090824b80, ffff888090825b80)
The buggy address belongs to the page:
page:ffffea0002420900 refcount:1 mapcount:0 mapping:ffff8880aa5f8a80 index:0x0 compound_mapcount: 0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea00016f8a88 ffffea00022d4788 ffff8880aa5f8a80
raw: 0000000000000000 ffff888090824b80 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888090824300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888090824380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888090824400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                                ^
 ffff888090824480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888090824500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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