KASAN: use-after-free Read in rxrpc_put_peer

From: syzbot
Date: Wed Aug 28 2019 - 15:48:10 EST

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Hello,

syzbot found the following crash on:

HEAD commit: ed2393ca Add linux-next specific files for 20190827
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=11b4a79c600000
kernel config: https://syzkaller.appspot.com/x/.config?x=2ef5940a07ed45f4
dashboard link: https://syzkaller.appspot.com/bug?extid=b9be979c55f2bea8ed30
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13c73066600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+b9be979c55f2bea8ed30@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: use-after-free in __rxrpc_put_peer net/rxrpc/peer_object.c:411 [inline]
BUG: KASAN: use-after-free in rxrpc_put_peer+0x685/0x6a0 net/rxrpc/peer_object.c:435
Read of size 8 at addr ffff8880a05bd218 by task ksoftirqd/1/16

CPU: 1 PID: 16 Comm: ksoftirqd/1 Not tainted 5.3.0-rc6-next-20190827 #74
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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_put_peer net/rxrpc/peer_object.c:411 [inline]
rxrpc_put_peer+0x685/0x6a0 net/rxrpc/peer_object.c:435
rxrpc_rcu_destroy_call+0x5e/0x140 net/rxrpc/call_object.c:566
__rcu_reclaim kernel/rcu/rcu.h:222 [inline]
rcu_do_batch kernel/rcu/tree.c:2157 [inline]
rcu_core+0x581/0x1560 kernel/rcu/tree.c:2377
rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2386
__do_softirq+0x262/0x98c kernel/softirq.c:292
run_ksoftirqd kernel/softirq.c:603 [inline]
run_ksoftirqd+0x8e/0x110 kernel/softirq.c:595
smpboot_thread_fn+0x6a3/0xa40 kernel/smpboot.c:165
kthread+0x361/0x430 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 17189:
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:552 [inline]
kzalloc include/linux/slab.h:686 [inline]
rxrpc_alloc_local net/rxrpc/local_object.c:79 [inline]
rxrpc_lookup_local+0x562/0x1ba0 net/rxrpc/local_object.c:277
rxrpc_sendmsg+0x379/0x5f0 net/rxrpc/af_rxrpc.c:566
sock_sendmsg_nosec net/socket.c:637 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:657
___sys_sendmsg+0x3e2/0x920 net/socket.c:2311
__sys_sendmmsg+0x1bf/0x4d0 net/socket.c:2413
__do_sys_sendmmsg net/socket.c:2442 [inline]
__se_sys_sendmmsg net/socket.c:2439 [inline]
__x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2439
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9:
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
rxrpc_local_rcu+0x62/0x80 net/rxrpc/local_object.c:499
__rcu_reclaim kernel/rcu/rcu.h:222 [inline]
rcu_do_batch kernel/rcu/tree.c:2157 [inline]
rcu_core+0x581/0x1560 kernel/rcu/tree.c:2377
rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2386
__do_softirq+0x262/0x98c kernel/softirq.c:292

The buggy address belongs to the object at ffff8880a05bd200
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 24 bytes inside of
1024-byte region [ffff8880a05bd200, ffff8880a05bd600)
The buggy address belongs to the page:
page:ffffea0002816f00 refcount:1 mapcount:0 mapping:ffff8880aa400c40 index:0xffff8880a05bcd80 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea00027c4588 ffffea0002381088 ffff8880aa400c40
raw: ffff8880a05bcd80 ffff8880a05bc000 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880a05bd100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880a05bd180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

ffff8880a05bd200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

^
ffff8880a05bd280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880a05bd300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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Next message: Josh Poimboeuf: "Re: next-20190826 - objtool fails to build."
Previous message: Matthew Wilcox: "Re: [PATCH v2 2/2] mm, sl[aou]b: guarantee natural alignment for kmalloc(power-of-two)"
Next in thread: David Howells: "Re: KASAN: use-after-free Read in rxrpc_put_peer"
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