[syzbot] KASAN: use-after-free Read in io_poll_remove_entries

[syzbot] KASAN: use-after-free Read in io_poll_remove_entries

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    8565d64430f8 Merge tag 'bounds-fixes-v5.18-rc1' of git://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15406ddb700000
kernel config:  https://syzkaller.appspot.com/x/.config?x=89040bbe61f60a52
dashboard link: https://syzkaller.appspot.com/bug?extid=cd301bb6523ea8cc8ca2
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cd301bb6523ea8cc8ca2@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in __list_del_entry_valid+0xe0/0xf0 lib/list_debug.c:51
Read of size 8 at addr ffff8880700bed30 by task syz-executor.2/5247

CPU: 0 PID: 5247 Comm: syz-executor.2 Tainted: G        W         5.17.0-syzkaller-01402-g8565d64430f8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_address_description.constprop.0.cold+0x8d/0x303 mm/kasan/report.c:255
 __kasan_report mm/kasan/report.c:442 [inline]
 kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
 __list_del_entry_valid+0xe0/0xf0 lib/list_debug.c:51
 __list_del_entry include/linux/list.h:134 [inline]
 list_del_init include/linux/list.h:206 [inline]
 io_poll_remove_entry fs/io_uring.c:5863 [inline]
 io_poll_remove_entries.part.0+0x167/0x7e0 fs/io_uring.c:5895
 io_poll_remove_entries fs/io_uring.c:5875 [inline]
 io_apoll_task_func+0xba/0x230 fs/io_uring.c:5995
 handle_tw_list fs/io_uring.c:2480 [inline]
 tctx_task_work+0x1a2/0x1380 fs/io_uring.c:2514
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 tracehook_notify_signal include/linux/tracehook.h:213 [inline]
 handle_signal_work kernel/entry/common.c:146 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:186 [inline]
 exit_to_user_mode_prepare+0x256/0x290 kernel/entry/common.c:221
 __syscall_exit_to_user_mode_work kernel/entry/common.c:303 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:314
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f2400e65049
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f23ff7da168 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
RAX: 0000000000001261 RBX: 00007f2400f77f60 RCX: 00007f2400e65049
RDX: 0000000000000000 RSI: 0000000000001261 RDI: 0000000000000004
RBP: 00007f2400ebf08d R08: 0000000000000000 R09: 0000000030000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd5a0e325f R14: 00007f23ff7da300 R15: 0000000000022000
 </TASK>

Allocated by task 5243:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:436 [inline]
 ____kasan_kmalloc mm/kasan/common.c:515 [inline]
 ____kasan_kmalloc mm/kasan/common.c:474 [inline]
 __kasan_kmalloc+0xa6/0xd0 mm/kasan/common.c:524
 kasan_kmalloc include/linux/kasan.h:249 [inline]
 kmem_cache_alloc_trace+0x1ea/0x4a0 mm/slab.c:3567
 kmalloc include/linux/slab.h:581 [inline]
 io_arm_poll_handler+0x39d/0x940 fs/io_uring.c:6248
 io_queue_sqe_arm_apoll+0x6d/0x430 fs/io_uring.c:7499
 __io_queue_sqe fs/io_uring.c:7541 [inline]
 io_queue_sqe fs/io_uring.c:7568 [inline]
 io_submit_sqe fs/io_uring.c:7776 [inline]
 io_submit_sqes+0x7dda/0x9310 fs/io_uring.c:7882
 __do_sys_io_uring_enter+0x9f1/0x1520 fs/io_uring.c:10924
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 5258:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 kasan_set_track+0x21/0x30 mm/kasan/common.c:45
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
 ____kasan_slab_free mm/kasan/common.c:366 [inline]
 ____kasan_slab_free+0xff/0x140 mm/kasan/common.c:328
 kasan_slab_free include/linux/kasan.h:215 [inline]
 __cache_free mm/slab.c:3437 [inline]
 kfree+0xf8/0x2b0 mm/slab.c:3794
 io_clean_op+0x20a/0xd90 fs/io_uring.c:7137
 io_dismantle_req fs/io_uring.c:2270 [inline]
 __io_free_req+0xc8/0x3c5 fs/io_uring.c:2280
 io_put_req_find_next fs/io_uring.c:2717 [inline]
 io_wq_free_work.cold+0x10/0x69 fs/io_uring.c:7301
 io_worker_handle_work+0xb3e/0x1b30 fs/io-wq.c:598
 io_wqe_worker+0x606/0xd40 fs/io-wq.c:642
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Last potentially related work creation:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 __kasan_record_aux_stack+0x7e/0x90 mm/kasan/generic.c:348
 kvfree_call_rcu+0x74/0x990 kernel/rcu/tree.c:3595
 cfg80211_update_known_bss+0x833/0xa60 net/wireless/scan.c:1661
 cfg80211_bss_update+0xef/0x2070 net/wireless/scan.c:1708
 cfg80211_inform_single_bss_frame_data+0x72b/0xf30 net/wireless/scan.c:2464
 cfg80211_inform_bss_frame_data+0xa7/0xb50 net/wireless/scan.c:2497
 ieee80211_bss_info_update+0x35b/0xb00 net/mac80211/scan.c:190
 ieee80211_rx_bss_info net/mac80211/ibss.c:1119 [inline]
 ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1610 [inline]
 ieee80211_ibss_rx_queued_mgmt+0x19cf/0x3150 net/mac80211/ibss.c:1639
 ieee80211_iface_process_skb net/mac80211/iface.c:1527 [inline]
 ieee80211_iface_work+0xa69/0xd00 net/mac80211/iface.c:1581
 process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
 worker_thread+0x657/0x1110 kernel/workqueue.c:2454
 kthread+0x2e9/0x3a0 kernel/kthread.c:377
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff8880700bed00
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 48 bytes inside of
 96-byte region [ffff8880700bed00, ffff8880700bed60)
The buggy address belongs to the page:
page:ffffea0001c02f80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x700be
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea0000736b88 ffffea0001eb7448 ffff888010c40300
raw: 0000000000000000 ffff8880700be000 0000000100000020 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x342220(__GFP_HIGH|__GFP_ATOMIC|__GFP_NOWARN|__GFP_COMP|__GFP_HARDWALL|__GFP_THISNODE), pid 0, ts 118360599722, free_ts 118282284710
 prep_new_page mm/page_alloc.c:2434 [inline]
 get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4165
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5389
 __alloc_pages_node include/linux/gfp.h:572 [inline]
 kmem_getpages mm/slab.c:1378 [inline]
 cache_grow_begin+0x75/0x390 mm/slab.c:2584
 cache_alloc_refill+0x27f/0x380 mm/slab.c:2957
 ____cache_alloc mm/slab.c:3040 [inline]
 ____cache_alloc mm/slab.c:3023 [inline]
 __do_cache_alloc mm/slab.c:3267 [inline]
 slab_alloc mm/slab.c:3308 [inline]
 kmem_cache_alloc_trace+0x380/0x4a0 mm/slab.c:3565
 kmalloc include/linux/slab.h:581 [inline]
 dst_cow_metrics_generic+0x48/0x1e0 net/core/dst.c:199
 dst_metrics_write_ptr include/net/dst.h:119 [inline]
 dst_metric_set include/net/dst.h:180 [inline]
 icmp6_dst_alloc+0x4fb/0x6c0 net/ipv6/route.c:3284
 ndisc_send_skb+0x1146/0x17f0 net/ipv6/ndisc.c:488
 ndisc_send_rs+0x12e/0x6f0 net/ipv6/ndisc.c:702
 addrconf_rs_timer+0x3f2/0x820 net/ipv6/addrconf.c:3915
 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
 expire_timers kernel/time/timer.c:1466 [inline]
 __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734
 __run_timers kernel/time/timer.c:1715 [inline]
 run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747
 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1352 [inline]
 free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1404
 free_unref_page_prepare mm/page_alloc.c:3325 [inline]
 free_unref_page+0x19/0x690 mm/page_alloc.c:3404
 slab_destroy mm/slab.c:1630 [inline]
 slabs_destroy+0x89/0xc0 mm/slab.c:1650
 cache_flusharray mm/slab.c:3410 [inline]
 ___cache_free+0x303/0x600 mm/slab.c:3472
 qlink_free mm/kasan/quarantine.c:157 [inline]
 qlist_free_all+0x50/0x1a0 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x97/0xb0 mm/kasan/common.c:446
 kasan_slab_alloc include/linux/kasan.h:239 [inline]
 slab_post_alloc_hook mm/slab.h:732 [inline]
 slab_alloc_node mm/slab.c:3253 [inline]
 kmem_cache_alloc_node+0x2ea/0x590 mm/slab.c:3591
 __alloc_skb+0x215/0x340 net/core/skbuff.c:414
 alloc_skb include/linux/skbuff.h:1158 [inline]
 alloc_skb_with_frags+0x93/0x620 net/core/skbuff.c:5956
 sock_alloc_send_pskb+0x793/0x920 net/core/sock.c:2586
 mld_newpack.isra.0+0x1be/0x750 net/ipv6/mcast.c:1746
 add_grhead+0x283/0x360 net/ipv6/mcast.c:1849
 add_grec+0x106a/0x1530 net/ipv6/mcast.c:1987
 mld_send_initial_cr.part.0+0xf6/0x230 net/ipv6/mcast.c:2234
 mld_send_initial_cr net/ipv6/mcast.c:1232 [inline]
 mld_dad_work+0x1d3/0x690 net/ipv6/mcast.c:2260

Memory state around the buggy address:
 ffff8880700bec00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff8880700bec80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>ffff8880700bed00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                                     ^
 ffff8880700bed80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff8880700bee00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
==================================================================


---
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Re: [syzbot] KASAN: use-after-free Read in io_poll_remove_entries

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    b47d5a4f6b8d Merge tag 'audit-pr-20220321' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10e8e8ed700000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c44f0c051803a0ae
dashboard link: https://syzkaller.appspot.com/bug?extid=cd301bb6523ea8cc8ca2
compiler:       Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=150525ed700000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10d08625700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cd301bb6523ea8cc8ca2@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in __list_del_entry_valid+0x76/0x100 lib/list_debug.c:51
Read of size 8 at addr ffff88801ecab630 by task syz-executor987/3638

CPU: 1 PID: 3638 Comm: syz-executor987 Tainted: G        W         5.17.0-syzkaller-01442-gb47d5a4f6b8d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1dc/0x2d8 lib/dump_stack.c:106
 print_address_description+0x65/0x3a0 mm/kasan/report.c:255
 __kasan_report mm/kasan/report.c:442 [inline]
 kasan_report+0x19a/0x1f0 mm/kasan/report.c:459
 __list_del_entry_valid+0x76/0x100 lib/list_debug.c:51
 __list_del_entry include/linux/list.h:134 [inline]
 list_del_init include/linux/list.h:206 [inline]
 io_poll_remove_entry fs/io_uring.c:5863 [inline]
 io_poll_remove_entries+0x1a8/0x5c0 fs/io_uring.c:5895
 io_apoll_task_func+0x7d/0x2c0 fs/io_uring.c:5995
 handle_tw_list fs/io_uring.c:2480 [inline]
 tctx_task_work+0xcf1/0x1130 fs/io_uring.c:2514
 task_work_run+0x146/0x1c0 kernel/task_work.c:164
 exit_task_work include/linux/task_work.h:32 [inline]
 do_exit+0x5e3/0x22a0 kernel/exit.c:806
 do_group_exit+0x2af/0x2b0 kernel/exit.c:936
 __do_sys_exit_group+0x13/0x20 kernel/exit.c:947
 __se_sys_exit_group+0x10/0x10 kernel/exit.c:945
 __x64_sys_exit_group+0x37/0x40 kernel/exit.c:945
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f0e18005c59
Code: Unable to access opcode bytes at RIP 0x7f0e18005c2f.
RSP: 002b:00007fff7d1f37a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f0e1807a330 RCX: 00007f0e18005c59
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0e1807a330
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001
 </TASK>

Allocated by task 3633:
 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:436 [inline]
 ____kasan_kmalloc+0xdc/0x110 mm/kasan/common.c:515
 kasan_kmalloc include/linux/kasan.h:249 [inline]
 kmem_cache_alloc_trace+0x9d/0x330 mm/slub.c:3257
 kmalloc include/linux/slab.h:581 [inline]
 io_arm_poll_handler+0x3bd/0x710 fs/io_uring.c:6248
 io_queue_sqe_arm_apoll fs/io_uring.c:7499 [inline]
 __io_queue_sqe+0x23d/0x10b0 fs/io_uring.c:7541
 io_queue_sqe fs/io_uring.c:7568 [inline]
 io_submit_sqe fs/io_uring.c:7776 [inline]
 io_submit_sqes+0x1265/0xb050 fs/io_uring.c:7882
 __do_sys_io_uring_enter fs/io_uring.c:10924 [inline]
 __se_sys_io_uring_enter+0x31f/0x2f50 fs/io_uring.c:10850
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 3633:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4c/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x126/0x180 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:215 [inline]
 slab_free_hook mm/slub.c:1728 [inline]
 slab_free_freelist_hook+0x12e/0x1a0 mm/slub.c:1754
 slab_free mm/slub.c:3509 [inline]
 kfree+0xb8/0x2e0 mm/slub.c:4562
 io_clean_op fs/io_uring.c:7137 [inline]
 io_dismantle_req+0x644/0x9b0 fs/io_uring.c:2270
 __io_req_complete_post+0x294/0x4b0 fs/io_uring.c:2108
 io_req_complete_post fs/io_uring.c:2121 [inline]
 io_req_complete_failed+0xd7/0x440 fs/io_uring.c:2152
 handle_tw_list fs/io_uring.c:2480 [inline]
 tctx_task_work+0xcf1/0x1130 fs/io_uring.c:2514
 task_work_run+0x146/0x1c0 kernel/task_work.c:164
 exit_task_work include/linux/task_work.h:32 [inline]
 do_exit+0x5e3/0x22a0 kernel/exit.c:806
 do_group_exit+0x2af/0x2b0 kernel/exit.c:936
 __do_sys_exit_group+0x13/0x20 kernel/exit.c:947
 __ia32_sys_exit_group+0x0/0x40 kernel/exit.c:945
 __x64_sys_exit_group+0x37/0x40 kernel/exit.c:945
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff88801ecab600
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 48 bytes inside of
 96-byte region [ffff88801ecab600, ffff88801ecab660)
The buggy address belongs to the page:
page:ffffea00007b2ac0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1ecab
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea00007c7580 dead000000000004 ffff888011441780
raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY), pid 2979, ts 18120987075, free_ts 18116591159
 prep_new_page mm/page_alloc.c:2434 [inline]
 get_page_from_freelist+0x729/0x9e0 mm/page_alloc.c:4165
 __alloc_pages+0x255/0x580 mm/page_alloc.c:5389
 alloc_slab_page mm/slub.c:1799 [inline]
 allocate_slab+0xce/0x3f0 mm/slub.c:1944
 new_slab mm/slub.c:2004 [inline]
 ___slab_alloc+0x3fe/0xc30 mm/slub.c:3018
 __slab_alloc mm/slub.c:3105 [inline]
 slab_alloc_node mm/slub.c:3196 [inline]
 slab_alloc mm/slub.c:3238 [inline]
 __kmalloc+0x2eb/0x380 mm/slub.c:4420
 kmalloc include/linux/slab.h:586 [inline]
 kzalloc include/linux/slab.h:714 [inline]
 tomoyo_encode2+0x25a/0x560 security/tomoyo/realpath.c:45
 tomoyo_encode security/tomoyo/realpath.c:80 [inline]
 tomoyo_realpath_from_path+0x5c3/0x610 security/tomoyo/realpath.c:288
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_check_open_permission+0x22f/0x490 security/tomoyo/file.c:771
 security_file_open+0x50/0x570 security/security.c:1651
 do_dentry_open+0x350/0x1020 fs/open.c:811
 do_open fs/namei.c:3476 [inline]
 path_openat+0x273b/0x36a0 fs/namei.c:3609
 do_filp_open+0x277/0x4f0 fs/namei.c:3636
 do_sys_openat2+0x13b/0x500 fs/open.c:1214
 do_sys_open fs/open.c:1230 [inline]
 __do_sys_openat fs/open.c:1246 [inline]
 __se_sys_openat fs/open.c:1241 [inline]
 __x64_sys_openat+0x243/0x290 fs/open.c:1241
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1352 [inline]
 free_pcp_prepare+0xd1c/0xe00 mm/page_alloc.c:1404
 free_unref_page_prepare mm/page_alloc.c:3325 [inline]
 free_unref_page+0x7d/0x580 mm/page_alloc.c:3404
 free_pipe_info+0x2f6/0x380 fs/pipe.c:851
 put_pipe_info fs/pipe.c:711 [inline]
 pipe_release+0x235/0x310 fs/pipe.c:734
 __fput+0x3fc/0x870 fs/file_table.c:317
 task_work_run+0x146/0x1c0 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:189 [inline]
 exit_to_user_mode_prepare+0x1dd/0x200 kernel/entry/common.c:221
 __syscall_exit_to_user_mode_work kernel/entry/common.c:303 [inline]
 syscall_exit_to_user_mode+0x2e/0x70 kernel/entry/common.c:314
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Memory state around the buggy address:
 ffff88801ecab500: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
 ffff88801ecab580: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
>ffff88801ecab600: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                                     ^
 ffff88801ecab680: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
 ffff88801ecab700: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
==================================================================

Re: [syzbot] KASAN: use-after-free Read in io_poll_remove_entries

[Jens Axboe]

#syz test: git://git.kernel.dk/linux-block for-5.18/io_uring

-- 
Jens Axboe

Re: [syzbot] KASAN: use-after-free Read in io_poll_remove_entries

[syzbot]

syzbot has bisected this issue to:

commit 91eac1c69c202d9dad8bf717ae5b92db70bfe5cf
Author: Jens Axboe <axboe@kernel.dk>
Date:   Wed Mar 16 22:59:10 2022 +0000

    io_uring: cache poll/double-poll state with a request flag

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=11819d0b700000
start commit:   b47d5a4f6b8d Merge tag 'audit-pr-20220321' of git://git.ke..
git tree:       upstream
final oops:     https://syzkaller.appspot.com/x/report.txt?x=13819d0b700000
console output: https://syzkaller.appspot.com/x/log.txt?x=15819d0b700000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c44f0c051803a0ae
dashboard link: https://syzkaller.appspot.com/bug?extid=cd301bb6523ea8cc8ca2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=150525ed700000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10d08625700000

Reported-by: syzbot+cd301bb6523ea8cc8ca2@syzkaller.appspotmail.com
Fixes: 91eac1c69c20 ("io_uring: cache poll/double-poll state with a request flag")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

Re: [syzbot] KASAN: use-after-free Read in io_poll_remove_entries

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+cd301bb6523ea8cc8ca2@syzkaller.appspotmail.com

Tested on:

commit:         7d58de1a io_uring: don't recycle provided buffer if pu..
git tree:       git://git.kernel.dk/linux-block for-5.18/io_uring
kernel config:  https://syzkaller.appspot.com/x/.config?x=198493467201ec16
dashboard link: https://syzkaller.appspot.com/bug?extid=cd301bb6523ea8cc8ca2
compiler:       Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.2

Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.