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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cb71b93c2dc3 Add linux-next specific files for 20220628
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13a297cc080000
kernel config: https://syzkaller.appspot.com/x/.config?x=badbc1adb2d582eb
dashboard link: https://syzkaller.appspot.com/bug?extid=382c8824777dca2812fe
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=115fdbec080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=132e4c92080000

Bisection is inconclusive: the issue happens on the oldest tested release.

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15a3c0a4080000
final oops: https://syzkaller.appspot.com/x/report.txt?x=17a3c0a4080000
console output: https://syzkaller.appspot.com/x/log.txt?x=13a3c0a4080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+382c88...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in kill_fasync+0x45e/0x470 fs/fcntl.c:1014
Read of size 8 at addr ffff88807dc93168 by task kworker/0:2/144

CPU: 0 PID: 144 Comm: kworker/0:2 Not tainted 5.19.0-rc4-next-20220628-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
Workqueue: events key_garbage_collector
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:317 [inline]
print_report.cold+0x2ba/0x719 mm/kasan/report.c:433
kasan_report+0xbe/0x1f0 mm/kasan/report.c:495
kill_fasync+0x45e/0x470 fs/fcntl.c:1014
post_one_notification.isra.0+0x6e4/0x990 kernel/watch_queue.c:128
remove_watch_from_object+0x35a/0x9d0 kernel/watch_queue.c:527
remove_watch_list include/linux/watch_queue.h:115 [inline]
key_gc_unused_keys.constprop.0+0x2e5/0x600 security/keys/gc.c:135
key_garbage_collector+0x3d7/0x920 security/keys/gc.c:297
process_one_work+0x991/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302
</TASK>

Allocated by task 5494:
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+0xa9/0xd0 mm/kasan/common.c:524
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:733 [inline]
alloc_pipe_info+0x105/0x590 fs/pipe.c:790
get_pipe_inode fs/pipe.c:881 [inline]
create_pipe_files+0x8d/0x880 fs/pipe.c:913
__do_pipe_flags fs/pipe.c:962 [inline]
do_pipe2+0x96/0x1b0 fs/pipe.c:1010
__do_sys_pipe2 fs/pipe.c:1028 [inline]
__se_sys_pipe2 fs/pipe.c:1026 [inline]
__x64_sys_pipe2+0x50/0x70 fs/pipe.c:1026
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+0x46/0xb0

Freed by task 5494:
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+0x166/0x1c0 mm/kasan/common.c:328
kasan_slab_free include/linux/kasan.h:200 [inline]
slab_free_hook mm/slub.c:1754 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1780
slab_free mm/slub.c:3534 [inline]
kfree+0xe2/0x4d0 mm/slub.c:4562
put_pipe_info fs/pipe.c:711 [inline]
pipe_release+0x2b6/0x310 fs/pipe.c:734
__fput+0x277/0x9d0 fs/file_table.c:317
task_work_run+0xdd/0x1a0 kernel/task_work.c:177
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0xaf1/0x29f0 kernel/exit.c:795
do_group_exit+0xd2/0x2f0 kernel/exit.c:925
__do_sys_exit_group kernel/exit.c:936 [inline]
__se_sys_exit_group kernel/exit.c:934 [inline]
__x64_sys_exit_group+0x3a/0x50 kernel/exit.c:934
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+0x46/0xb0

The buggy address belongs to the object at ffff88807dc93000
which belongs to the cache kmalloc-cg-512 of size 512
The buggy address is located 360 bytes inside of
512-byte region [ffff88807dc93000, ffff88807dc93200)

The buggy address belongs to the physical page:
page:ffffea0001f72400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7dc90
head:ffffea0001f72400 order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888011842dc0
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5470, tgid 5470 (syz-executor105), ts 76271246150, free_ts 76264094282
prep_new_page mm/page_alloc.c:2535 [inline]
get_page_from_freelist+0x210d/0x3a30 mm/page_alloc.c:4282
__alloc_pages+0x1c7/0x510 mm/page_alloc.c:5506
alloc_pages+0x1aa/0x310 mm/mempolicy.c:2280
alloc_slab_page mm/slub.c:1824 [inline]
allocate_slab+0x27e/0x3d0 mm/slub.c:1969
new_slab mm/slub.c:2029 [inline]
___slab_alloc+0x89d/0xef0 mm/slub.c:3031
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3118
slab_alloc_node mm/slub.c:3209 [inline]
slab_alloc mm/slub.c:3251 [inline]
kmem_cache_alloc_trace+0x323/0x3e0 mm/slub.c:3282
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:733 [inline]
alloc_pipe_info+0x105/0x590 fs/pipe.c:790
get_pipe_inode fs/pipe.c:881 [inline]
create_pipe_files+0x8d/0x880 fs/pipe.c:913
__do_pipe_flags fs/pipe.c:962 [inline]
do_pipe2+0x96/0x1b0 fs/pipe.c:1010
__do_sys_pipe2 fs/pipe.c:1028 [inline]
__se_sys_pipe2 fs/pipe.c:1026 [inline]
__x64_sys_pipe2+0x50/0x70 fs/pipe.c:1026
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+0x46/0xb0
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1453 [inline]
free_pcp_prepare+0x5e4/0xd20 mm/page_alloc.c:1503
free_unref_page_prepare mm/page_alloc.c:3383 [inline]
free_unref_page+0x19/0x4d0 mm/page_alloc.c:3479
__stack_depot_save+0x168/0x500 lib/stackdepot.c:489
kasan_save_stack+0x2e/0x40 mm/kasan/common.c:39
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+0xa9/0xd0 mm/kasan/common.c:524
kmalloc include/linux/slab.h:605 [inline]
kzalloc include/linux/slab.h:733 [inline]
kobject_get_path+0xbe/0x230 lib/kobject.c:147
kobject_uevent_env+0x254/0x1640 lib/kobject_uevent.c:529
call_crda+0x17e/0x3b0 net/wireless/reg.c:583
reg_query_database net/wireless/reg.c:1158 [inline]
reg_process_hint_core net/wireless/reg.c:2693 [inline]
reg_process_hint+0x925/0x1710 net/wireless/reg.c:3036
reg_process_pending_hints net/wireless/reg.c:3124 [inline]
reg_todo+0x1a5/0x7d0 net/wireless/reg.c:3212
process_one_work+0x991/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302

Memory state around the buggy address:
ffff88807dc93000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807dc93080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807dc93100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88807dc93180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807dc93200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

[Hillf Danton]

On Sun, 10 Jul 2022 23:41:22 -0700

Post no notification in case of defunct.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git cb71b93c2dc3

--- y/kernel/watch_queue.c
+++ w/kernel/watch_queue.c
@@ -83,11 +83,13 @@ static bool post_one_notification(struct
if (!pipe)
return false;

+ spin_lock_bh(&wqueue->lock);
+ if (wqueue->defunct) {
+ spin_unlock_bh(&wqueue->lock);
+ return false;
+ }
spin_lock_irq(&pipe->rd_wait.lock);

- if (wqueue->defunct)
- goto out;
-
mask = pipe->ring_size - 1;
head = pipe->head;
tail = pipe->tail;
@@ -124,6 +126,7 @@ static bool post_one_notification(struct

out:
spin_unlock_irq(&pipe->rd_wait.lock);
+ spin_unlock_bh(&wqueue->lock);
if (done)
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
return done;
--

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: use-after-free Read in kill_fasync

IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready
Bluetooth: hci0: command 0x0409 tx timeout

==================================================================
BUG: KASAN: use-after-free in kill_fasync+0x45e/0x470 fs/fcntl.c:1014

Read of size 8 at addr ffff88807d1e9168 by task kworker/1:3/3621

CPU: 1 PID: 3621 Comm: kworker/1:3 Not tainted 5.19.0-rc4-next-20220628-syzkaller-dirty #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
Workqueue: events key_garbage_collector
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:317 [inline]
print_report.cold+0x2ba/0x719 mm/kasan/report.c:433
kasan_report+0xbe/0x1f0 mm/kasan/report.c:495
kill_fasync+0x45e/0x470 fs/fcntl.c:1014

post_one_notification.isra.0+0x71a/0x9d0 kernel/watch_queue.c:131
remove_watch_from_object+0x35a/0x9d0 kernel/watch_queue.c:530

remove_watch_list include/linux/watch_queue.h:115 [inline]
key_gc_unused_keys.constprop.0+0x2e5/0x600 security/keys/gc.c:135
key_garbage_collector+0x3d7/0x920 security/keys/gc.c:297
process_one_work+0x991/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302
</TASK>

Allocated by task 4105:

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+0xa9/0xd0 mm/kasan/common.c:524
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:733 [inline]
alloc_pipe_info+0x105/0x590 fs/pipe.c:790
get_pipe_inode fs/pipe.c:881 [inline]
create_pipe_files+0x8d/0x880 fs/pipe.c:913
__do_pipe_flags fs/pipe.c:962 [inline]
do_pipe2+0x96/0x1b0 fs/pipe.c:1010
__do_sys_pipe2 fs/pipe.c:1028 [inline]
__se_sys_pipe2 fs/pipe.c:1026 [inline]
__x64_sys_pipe2+0x50/0x70 fs/pipe.c:1026
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+0x46/0xb0

Freed by task 4104:

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+0x166/0x1c0 mm/kasan/common.c:328
kasan_slab_free include/linux/kasan.h:200 [inline]
slab_free_hook mm/slub.c:1754 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1780
slab_free mm/slub.c:3534 [inline]
kfree+0xe2/0x4d0 mm/slub.c:4562
put_pipe_info fs/pipe.c:711 [inline]
pipe_release+0x2b6/0x310 fs/pipe.c:734
__fput+0x277/0x9d0 fs/file_table.c:317
task_work_run+0xdd/0x1a0 kernel/task_work.c:177

resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop kernel/entry/common.c:169 [inline]
exit_to_user_mode_prepare+0x23c/0x250 kernel/entry/common.c:201
__syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:294
do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x46/0xb0

The buggy address belongs to the object at ffff88807d1e9000

which belongs to the cache kmalloc-cg-512 of size 512
The buggy address is located 360 bytes inside of

512-byte region [ffff88807d1e9000, ffff88807d1e9200)

The buggy address belongs to the physical page:

page:ffffea0001f47a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7d1e8
head:ffffea0001f47a00 order:2 compound_mapcount:0 compound_pincount:0
memcg:ffff88807c9f0b01

flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)

raw: 00fff00000010200 0000000000000000 dead000000000001 ffff888011842dc0
raw: 0000000000000000 0000000080100010 00000001ffffffff ffff88807c9f0b01

page dumped because: kasan: bad access detected
page_owner tracks the page as allocated

page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 2958, tgid 2958 (klogd), ts 15679614274, free_ts 14007295278

prep_new_page mm/page_alloc.c:2535 [inline]
get_page_from_freelist+0x210d/0x3a30 mm/page_alloc.c:4282
__alloc_pages+0x1c7/0x510 mm/page_alloc.c:5506
alloc_pages+0x1aa/0x310 mm/mempolicy.c:2280
alloc_slab_page mm/slub.c:1824 [inline]
allocate_slab+0x27e/0x3d0 mm/slub.c:1969
new_slab mm/slub.c:2029 [inline]
___slab_alloc+0x89d/0xef0 mm/slub.c:3031
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3118
slab_alloc_node mm/slub.c:3209 [inline]

__kmalloc_node_track_caller+0x360/0x480 mm/slub.c:4955
kmalloc_reserve net/core/skbuff.c:358 [inline]
__alloc_skb+0xd9/0x340 net/core/skbuff.c:430
alloc_skb include/linux/skbuff.h:1249 [inline]
alloc_skb_with_frags+0x93/0x6d0 net/core/skbuff.c:5990
sock_alloc_send_pskb+0x793/0x920 net/core/sock.c:2663
unix_dgram_sendmsg+0x415/0x1b60 net/unix/af_unix.c:1884
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:734
__sys_sendto+0x21a/0x320 net/socket.c:2116
__do_sys_sendto net/socket.c:2128 [inline]
__se_sys_sendto net/socket.c:2124 [inline]
__x64_sys_sendto+0xdd/0x1b0 net/socket.c:2124

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+0x46/0xb0
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1453 [inline]
free_pcp_prepare+0x5e4/0xd20 mm/page_alloc.c:1503
free_unref_page_prepare mm/page_alloc.c:3383 [inline]
free_unref_page+0x19/0x4d0 mm/page_alloc.c:3479

free_contig_range+0xb1/0x180 mm/page_alloc.c:9400
destroy_args+0xa8/0x64c mm/debug_vm_pgtable.c:1031
debug_vm_pgtable+0x2954/0x29e5 mm/debug_vm_pgtable.c:1354
do_one_initcall+0xfe/0x650 init/main.c:1300
do_initcall_level init/main.c:1375 [inline]
do_initcalls init/main.c:1391 [inline]
do_basic_setup init/main.c:1410 [inline]
kernel_init_freeable+0x6b1/0x73a init/main.c:1617
kernel_init+0x1a/0x1d0 init/main.c:1506

ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302

Memory state around the buggy address:

ffff88807d1e9000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807d1e9080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807d1e9100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88807d1e9180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807d1e9200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


Tested on:

commit: cb71b93c Add linux-next specific files for 20220628
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=134d24c8080000
kernel config: https://syzkaller.appspot.com/x/.config?x=695e91d821f66ab5

dashboard link: https://syzkaller.appspot.com/bug?extid=382c8824777dca2812fe
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=105a9782080000

[Hillf Danton]

On Sun, 10 Jul 2022 23:41:22 -0700

Post no notification in case of defunct.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git cb71b93c2dc3

--- y/kernel/watch_queue.c
+++ w/kernel/watch_queue.c
@@ -83,11 +83,13 @@ static bool post_one_notification(struct
if (!pipe)
return false;

+ spin_lock_bh(&wqueue->lock);
+ if (wqueue->defunct) {
+ spin_unlock_bh(&wqueue->lock);
+ return false;
+ }
spin_lock_irq(&pipe->rd_wait.lock);

- if (wqueue->defunct)
- goto out;
-
mask = pipe->ring_size - 1;
head = pipe->head;
tail = pipe->tail;

@@ -126,6 +128,7 @@ out:
spin_unlock_irq(&pipe->rd_wait.lock);

if (done)
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);

+ spin_unlock_bh(&wqueue->lock);
return done;

lost:
--

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+382c88...@syzkaller.appspotmail.com

Tested on:

commit: cb71b93c Add linux-next specific files for 20220628
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git

console output: https://syzkaller.appspot.com/x/log.txt?x=1573452c080000
kernel config: https://syzkaller.appspot.com/x/.config?x=695e91d821f66ab5

dashboard link: https://syzkaller.appspot.com/bug?extid=382c8824777dca2812fe
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=11bdab34080000

Note: testing is done by a robot and is best-effort only.

[syzbot]

syzbot suspects this issue was fixed by commit:

commit 69d4c0d3218692ffa56b0e1b9c76c50c699d7044
Author: Peter Zijlstra <pet...@infradead.org>
Date: Thu Jan 12 19:43:58 2023 +0000

entry, kasan, x86: Disallow overriding mem*() functions

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17adfae4c80000
start commit: 972a278fe60c Merge tag 'for-5.19-rc7-tag' of git://git.ker..
git tree: upstream
kernel config: https://syzkaller.appspot.com/x/.config?x=3cc990589d31f8d6
dashboard link: https://syzkaller.appspot.com/bug?extid=382c8824777dca2812fe
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=141c2dac080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1590cfa4080000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: entry, kasan, x86: Disallow overriding mem*() functions

[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.