Subject: [syzbot] [net?] [virt?] [kvm?] KASAN: slab-use-after-free Read in __vhost_vq_attach_worker

From: syzbot <[email-masked]>
Date: Mon, 26 Jun 2023 00:06:54 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    8d2be868b42c Add linux-next specific files for 20230623
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=12872950a80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d8ac8dd33677e8e0
dashboard link: https://syzkaller.appspot.com/bug?extid=8540db210d403f1aa214
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=15c1b70f280000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=122ee4cb280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2a004483aca3/disk-8d2be868.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5688cb13b277/vmlinux-8d2be868.xz
kernel image: https://storage.googleapis.com/syzbot-assets/76de0b63bc53/bzImage-8d2be868.xz

The issue was bisected to:

commit 21a18f4a51896fde11002165f0e7340f4131d6a0
Author: Mike Christie <[email-masked]>
Date:   Tue Jun 13 01:32:46 2023 +0000

    vhost: allow userspace to create workers

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=130850bf280000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=108850bf280000
console output: https://syzkaller.appspot.com/x/log.txt?x=170850bf280000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]
Fixes: 21a18f4a5189 ("vhost: allow userspace to create workers")

==================================================================
BUG: KASAN: slab-use-after-free in __mutex_lock_common kernel/locking/mutex.c:582 [inline]
BUG: KASAN: slab-use-after-free in __mutex_lock+0x1029/0x1350 kernel/locking/mutex.c:747
Read of size 8 at addr ffff8880703fff68 by task syz-executor204/5105

CPU: 0 PID: 5105 Comm: syz-executor204 Not tainted 6.4.0-rc7-next-20230623-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
 print_address_description.constprop.0+0x2c/0x3c0 mm/kasan/report.c:364
 print_report mm/kasan/report.c:475 [inline]
 kasan_report+0x11d/0x130 mm/kasan/report.c:588
 __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 __mutex_lock+0x1029/0x1350 kernel/locking/mutex.c:747
 __vhost_vq_attach_worker+0xe7/0x390 drivers/vhost/vhost.c:678
 vhost_dev_set_owner+0x670/0xa60 drivers/vhost/vhost.c:892
 vhost_net_set_owner drivers/vhost/net.c:1687 [inline]
 vhost_net_ioctl+0x668/0x16a0 drivers/vhost/net.c:1737
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0x19d/0x210 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fe7a9715629
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 21 19 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe7a96ba208 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000000000b RCX: 00007fe7a9715629
RDX: 0000000000000000 RSI: 000000000000af01 RDI: 0000000000000003
RBP: 00007fe7a979e240 R08: 00007fe7a979e248 R09: 00007fe7a979e248
R10: 00007fe7a979e248 R11: 0000000000000246 R12: 00007fe7a979e24c
R13: 00007ffcfa04d48f R14: 00007fe7a96ba300 R15: 0000000000022000
 </TASK>

Allocated by task 5105:
 kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
 kasan_set_track+0x25/0x30 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 ____kasan_kmalloc mm/kasan/common.c:333 [inline]
 __kasan_kmalloc+0xa2/0xb0 mm/kasan/common.c:383
 kmalloc include/linux/slab.h:579 [inline]
 kzalloc include/linux/slab.h:700 [inline]
 vhost_worker_create+0x9c/0x320 drivers/vhost/vhost.c:627
 vhost_dev_set_owner+0x5b9/0xa60 drivers/vhost/vhost.c:885
 vhost_net_set_owner drivers/vhost/net.c:1687 [inline]
 vhost_net_ioctl+0x668/0x16a0 drivers/vhost/net.c:1737
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0x19d/0x210 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 5108:
 kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
 kasan_set_track+0x25/0x30 mm/kasan/common.c:52
 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:521
 ____kasan_slab_free mm/kasan/common.c:236 [inline]
 ____kasan_slab_free+0x160/0x1c0 mm/kasan/common.c:200
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1792 [inline]
 slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1818
 slab_free mm/slub.c:3801 [inline]
 __kmem_cache_free+0xb8/0x2d0 mm/slub.c:3814
 vhost_worker_destroy drivers/vhost/vhost.c:600 [inline]
 vhost_workers_free drivers/vhost/vhost.c:615 [inline]
 vhost_dev_cleanup+0x66b/0x850 drivers/vhost/vhost.c:991
 vhost_dev_reset_owner+0x25/0x160 drivers/vhost/vhost.c:923
 vhost_net_reset_owner drivers/vhost/net.c:1621 [inline]
 vhost_net_ioctl+0x807/0x16a0 drivers/vhost/net.c:1735
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0x19d/0x210 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff8880703fff00
 which belongs to the cache kmalloc-cg-192 of size 192
The buggy address is located 104 bytes inside of
 freed 192-byte region [ffff8880703fff00, ffff8880703fffc0)

The buggy address belongs to the physical page:
page:ffffea0001c0ffc0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x703ff
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000200 ffff88801284ddc0 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000100010 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 0x16cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_RETRY_MAYFAIL|__GFP_NORETRY), pid 5034, tgid 5034 (syz-executor204), ts 72916757418, free_ts 72797036103
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x2db/0x350 mm/page_alloc.c:1570
 prep_new_page mm/page_alloc.c:1577 [inline]
 get_page_from_freelist+0xfd9/0x2c40 mm/page_alloc.c:3257
 __alloc_pages+0x1cb/0x4a0 mm/page_alloc.c:4513
 alloc_pages+0x1aa/0x270 mm/mempolicy.c:2279
 alloc_slab_page mm/slub.c:1862 [inline]
 allocate_slab+0x25f/0x390 mm/slub.c:2009
 new_slab mm/slub.c:2062 [inline]
 ___slab_alloc+0xbc3/0x15d0 mm/slub.c:3215
 __slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3314
 __slab_alloc_node mm/slub.c:3367 [inline]
 slab_alloc_node mm/slub.c:3460 [inline]
 __kmem_cache_alloc_node+0x143/0x350 mm/slub.c:3509
 __do_kmalloc_node mm/slab_common.c:984 [inline]
 __kmalloc_node+0x51/0x1a0 mm/slab_common.c:992
 kmalloc_node include/linux/slab.h:599 [inline]
 kvmalloc_node+0xa2/0x1a0 mm/util.c:604
 kvmalloc include/linux/slab.h:717 [inline]
 kvzalloc include/linux/slab.h:725 [inline]
 netif_alloc_rx_queues net/core/dev.c:9847 [inline]
 alloc_netdev_mqs+0xbde/0x1270 net/core/dev.c:10660
 ieee80211_if_add+0x1b7/0x19d0 net/mac80211/iface.c:2099
 ieee80211_register_hw+0x37e5/0x40e0 net/mac80211/main.c:1407
 mac80211_hwsim_new_radio+0x26e6/0x4c70 drivers/net/wireless/virtual/mac80211_hwsim.c:5303
 hwsim_new_radio_nl+0xacf/0x1210 drivers/net/wireless/virtual/mac80211_hwsim.c:5983
 genl_family_rcv_msg_doit.isra.0+0x1e6/0x2d0 net/netlink/genetlink.c:970
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1161 [inline]
 free_unref_page_prepare+0x62e/0xcb0 mm/page_alloc.c:2384
 free_unref_page+0x33/0x370 mm/page_alloc.c:2479
 __unfreeze_partials+0x1fe/0x220 mm/slub.c:2647
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x195/0x220 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x63/0x90 mm/kasan/common.c:305
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook mm/slab.h:750 [inline]
 slab_alloc_node mm/slub.c:3470 [inline]
 __kmem_cache_alloc_node+0x1ce/0x350 mm/slub.c:3509
 __do_kmalloc_node mm/slab_common.c:984 [inline]
 __kmalloc_node+0x51/0x1a0 mm/slab_common.c:992
 kmalloc_node include/linux/slab.h:599 [inline]
 kvmalloc_node+0xa2/0x1a0 mm/util.c:604
 kvmalloc include/linux/slab.h:717 [inline]
 seq_buf_alloc fs/seq_file.c:38 [inline]
 seq_read_iter+0x7fb/0x12d0 fs/seq_file.c:210
 kernfs_fop_read_iter+0x4ce/0x690 fs/kernfs/file.c:279
 call_read_iter include/linux/fs.h:1865 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x4a8/0x8d0 fs/read_write.c:470
 ksys_read+0x122/0x250 fs/read_write.c:613
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
 ffff8880703ffe00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880703ffe80: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
>ffff8880703fff00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                          ^
 ffff8880703fff80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888070400000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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