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BUG: KASAN: use-after-free in rxrpc_send_keepalive+0x8a2/0x940 net/rxrpc/output.c:634
Read of size 8 at addr ffff8880a4599818 by task kworker/0:4/8855

CPU: 0 PID: 8855 Comm: kworker/0:4 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: krxrpcd rxrpc_peer_keepalive_worker
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:634
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 rxrpc_send_keepalive+0x8a2/0x940 net/rxrpc/output.c:634
 rxrpc_peer_keepalive_dispatch net/rxrpc/peer_event.c:369 [inline]
 rxrpc_peer_keepalive_worker+0x7be/0xd02 net/rxrpc/peer_event.c:430
 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 8710:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc mm/kasan/common.c:510 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:483
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:524
 kmem_cache_alloc_trace+0x158/0x790 mm/slab.c:3550
 kmalloc include/linux/slab.h:556 [inline]
 syslog_print kernel/printk/printk.c:1356 [inline]
 do_syslog kernel/printk/printk.c:1529 [inline]
 do_syslog+0x5fa/0x1820 kernel/printk/printk.c:1503
 kmsg_read+0x8f/0xc0 fs/proc/kmsg.c:40
 proc_reg_read+0x1fc/0x2c0 fs/proc/inode.c:223
 __vfs_read+0x8a/0x110 fs/read_write.c:425
 vfs_read+0x1f0/0x440 fs/read_write.c:461
 ksys_read+0x14f/0x290 fs/read_write.c:587
 __do_sys_read fs/read_write.c:597 [inline]
 __se_sys_read fs/read_write.c:595 [inline]
 __x64_sys_read+0x73/0xb0 fs/read_write.c:595
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 8710:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 kasan_set_free_info mm/kasan/common.c:332 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:471
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
 __cache_free mm/slab.c:3425 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3756
 syslog_print kernel/printk/printk.c:1415 [inline]
 do_syslog kernel/printk/printk.c:1529 [inline]
 do_syslog+0x918/0x1820 kernel/printk/printk.c:1503
 kmsg_read+0x8f/0xc0 fs/proc/kmsg.c:40
 proc_reg_read+0x1fc/0x2c0 fs/proc/inode.c:223
 __vfs_read+0x8a/0x110 fs/read_write.c:425
 vfs_read+0x1f0/0x440 fs/read_write.c:461
 ksys_read+0x14f/0x290 fs/read_write.c:587
 __do_sys_read fs/read_write.c:597 [inline]
 __se_sys_read fs/read_write.c:595 [inline]
 __x64_sys_read+0x73/0xb0 fs/read_write.c:595
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880a4599800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 24 bytes inside of
 1024-byte region [ffff8880a4599800, ffff8880a4599c00)
The buggy address belongs to the page:
page:ffffea0002916640 refcount:1 mapcount:0 mapping:ffff8880aa400c40 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea000246fa88 ffffea00024f1808 ffff8880aa400c40
raw: 0000000000000000 ffff8880a4599000 0000000100000002 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a4599700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a4599780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a4599800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff8880a4599880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a4599900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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