[syzbot] KASAN: use-after-free Read in free_netdev (3)

55 views

Skip to first unread message

syzbot

unread,

Jun 21, 2022, 9:01:26 PM6/21/22

to and...@kernel.org, a...@kernel.org, b...@vger.kernel.org, dan...@iogearbox.net, da...@davemloft.net, edum...@google.com, ha...@kernel.org, ido...@nvidia.com, john.fa...@gmail.com, ka...@fb.com, kps...@kernel.org, ku...@kernel.org, linux-...@vger.kernel.org, net...@vger.kernel.org, pab...@redhat.com, pe...@nvidia.com, songliu...@fb.com, syzkall...@googlegroups.com, y...@fb.com

Hello,

syzbot found the following issue on:

HEAD commit: b4a028c4d031 ipv4: ping: fix bind address validity check
git tree: net
console+strace: https://syzkaller.appspot.com/x/log.txt?x=17a3ab08080000
kernel config: https://syzkaller.appspot.com/x/.config?x=70e1a4d352a3c6ae
dashboard link: https://syzkaller.appspot.com/bug?extid=b75c138e9286ac742647
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=15506c60080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=116b6628080000

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

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15270be8080000
final oops: https://syzkaller.appspot.com/x/report.txt?x=17270be8080000
console output: https://syzkaller.appspot.com/x/log.txt?x=13270be8080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b75c13...@syzkaller.appspotmail.com

netlink: 20 bytes leftover after parsing attributes in process `syz-executor304'.
==================================================================
BUG: KASAN: use-after-free in free_netdev+0x58c/0x620 net/core/dev.c:10704
Read of size 8 at addr ffff88807e9de738 by task syz-executor304/3633

CPU: 1 PID: 3633 Comm: syz-executor304 Not tainted 5.19.0-rc2-syzkaller-00103-gb4a028c4d031 #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+0xeb/0x495 mm/kasan/report.c:313
print_report mm/kasan/report.c:429 [inline]
kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491
free_netdev+0x58c/0x620 net/core/dev.c:10704
netdev_run_todo+0xb48/0x10f0 net/core/dev.c:10356
rtnl_unlock net/core/rtnetlink.c:147 [inline]
rtnetlink_rcv_msg+0x447/0xc90 net/core/rtnetlink.c:6090
netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2501
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x543/0x7f0 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x917/0xe10 net/netlink/af_netlink.c:1921
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:734
____sys_sendmsg+0x6eb/0x810 net/socket.c:2492
___sys_sendmsg+0xf3/0x170 net/socket.c:2546
__sys_sendmsg net/socket.c:2575 [inline]
__do_sys_sendmsg net/socket.c:2584 [inline]
__se_sys_sendmsg net/socket.c:2582 [inline]
__x64_sys_sendmsg+0x132/0x220 net/socket.c:2582
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
RIP: 0033:0x7fae52dad6e9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 a1 15 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:00007fae52d5b308 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fae52e364e8 RCX: 00007fae52dad6e9
RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000004
RBP: 00007fae52e364e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fae52e364ec
R13: 00007fae52e03494 R14: 74656e2f7665642f R15: 0000000000022000
</TASK>

Allocated by task 3633:
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:605 [inline]
sk_prot_alloc+0x110/0x290 net/core/sock.c:1975
sk_alloc+0x36/0x770 net/core/sock.c:2028
tun_chr_open+0x7b/0x540 drivers/net/tun.c:3408
misc_open+0x376/0x4a0 drivers/char/misc.c:143
chrdev_open+0x266/0x770 fs/char_dev.c:414
do_dentry_open+0x4a1/0x11f0 fs/open.c:848
do_open fs/namei.c:3520 [inline]
path_openat+0x1c71/0x2910 fs/namei.c:3653
do_filp_open+0x1aa/0x400 fs/namei.c:3680
do_sys_openat2+0x16d/0x4c0 fs/open.c:1278
do_sys_open fs/open.c:1294 [inline]
__do_sys_openat fs/open.c:1310 [inline]
__se_sys_openat fs/open.c:1305 [inline]
__x64_sys_openat+0x13f/0x1f0 fs/open.c:1305
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 3634:
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+0x166/0x1a0 mm/kasan/common.c:328
kasan_slab_free include/linux/kasan.h:200 [inline]
slab_free_hook mm/slub.c:1727 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1753
slab_free mm/slub.c:3507 [inline]
kfree+0xd6/0x4d0 mm/slub.c:4555
sk_prot_free net/core/sock.c:2011 [inline]
__sk_destruct+0x5e5/0x710 net/core/sock.c:2097
sk_destruct net/core/sock.c:2112 [inline]
__sk_free+0x1a4/0x4a0 net/core/sock.c:2123
sk_free+0x78/0xa0 net/core/sock.c:2134
sock_put include/net/sock.h:1927 [inline]
__tun_detach+0xdb7/0x13e0 drivers/net/tun.c:680
tun_detach drivers/net/tun.c:692 [inline]
tun_chr_close+0x15c/0x180 drivers/net/tun.c:3444
__fput+0x277/0x9d0 fs/file_table.c:317
task_work_run+0xdd/0x1a0 kernel/task_work.c:177
ptrace_notify+0x114/0x140 kernel/signal.c:2353
ptrace_report_syscall include/linux/ptrace.h:420 [inline]
ptrace_report_syscall_exit include/linux/ptrace.h:482 [inline]
syscall_exit_work kernel/entry/common.c:249 [inline]
syscall_exit_to_user_mode_prepare+0xdb/0x230 kernel/entry/common.c:276
__syscall_exit_to_user_mode_work kernel/entry/common.c:281 [inline]
syscall_exit_to_user_mode+0x9/0x50 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 ffff88807e9de000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 1848 bytes inside of
4096-byte region [ffff88807e9de000, ffff88807e9df000)

The buggy address belongs to the physical page:
page:ffffea0001fa7600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7e9d8
head:ffffea0001fa7600 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888011842140
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 2984, tgid 2984 (udevd), ts 16101031779, free_ts 16095933951
prep_new_page mm/page_alloc.c:2456 [inline]
get_page_from_freelist+0x1290/0x3b70 mm/page_alloc.c:4198
__alloc_pages+0x1c7/0x510 mm/page_alloc.c:5426
alloc_pages+0x1aa/0x310 mm/mempolicy.c:2272
alloc_slab_page mm/slub.c:1797 [inline]
allocate_slab+0x26c/0x3c0 mm/slub.c:1942
new_slab mm/slub.c:2002 [inline]
___slab_alloc+0x985/0xd90 mm/slub.c:3002
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3089
slab_alloc_node mm/slub.c:3180 [inline]
slab_alloc mm/slub.c:3222 [inline]
__kmalloc+0x318/0x350 mm/slub.c:4413
kmalloc include/linux/slab.h:605 [inline]
tomoyo_realpath_from_path+0xc3/0x620 security/tomoyo/realpath.c:254
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_check_open_permission+0x272/0x380 security/tomoyo/file.c:771
tomoyo_file_open security/tomoyo/tomoyo.c:320 [inline]
tomoyo_file_open+0x9d/0xc0 security/tomoyo/tomoyo.c:315
security_file_open+0x45/0xb0 security/security.c:1645
do_dentry_open+0x349/0x11f0 fs/open.c:835
do_open fs/namei.c:3520 [inline]
path_openat+0x1c71/0x2910 fs/namei.c:3653
do_filp_open+0x1aa/0x400 fs/namei.c:3680
do_sys_openat2+0x16d/0x4c0 fs/open.c:1278
do_sys_open fs/open.c:1294 [inline]
__do_sys_openat fs/open.c:1310 [inline]
__se_sys_openat fs/open.c:1305 [inline]
__x64_sys_openat+0x13f/0x1f0 fs/open.c:1305
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1371 [inline]
free_pcp_prepare+0x549/0xd20 mm/page_alloc.c:1421
free_unref_page_prepare mm/page_alloc.c:3343 [inline]
free_unref_page+0x19/0x6a0 mm/page_alloc.c:3438
__unfreeze_partials+0x17c/0x1a0 mm/slub.c:2521
qlink_free mm/kasan/quarantine.c:168 [inline]
qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:187
kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:294
__kasan_slab_alloc+0xa2/0xc0 mm/kasan/common.c:446
kasan_slab_alloc include/linux/kasan.h:224 [inline]
slab_post_alloc_hook mm/slab.h:750 [inline]
slab_alloc_node mm/slub.c:3214 [inline]
slab_alloc mm/slub.c:3222 [inline]
__kmem_cache_alloc_lru mm/slub.c:3229 [inline]
kmem_cache_alloc_lru+0x31a/0x720 mm/slub.c:3246
__d_alloc+0x32/0x960 fs/dcache.c:1769
d_alloc+0x4a/0x230 fs/dcache.c:1849
d_alloc_parallel+0xe7/0x1af0 fs/dcache.c:2601
__lookup_slow+0x193/0x480 fs/namei.c:1686
lookup_slow fs/namei.c:1718 [inline]
walk_component+0x40f/0x6a0 fs/namei.c:2014
lookup_last fs/namei.c:2469 [inline]
path_lookupat+0x1bb/0x860 fs/namei.c:2493
filename_lookup+0x1c6/0x590 fs/namei.c:2522
vfs_statx+0x148/0x390 fs/stat.c:228
vfs_fstatat+0x8c/0xb0 fs/stat.c:255

Memory state around the buggy address:
ffff88807e9de600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807e9de680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807e9de700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88807e9de780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807e9de800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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

unread,

Jun 23, 2022, 8:21:33 AM6/23/22

to syzbot, linux-...@vger.kernel.org, syzkall...@googlegroups.com

On Tue, 21 Jun 2022 18:01:24 -0700

See if it is due to undeleted tun file.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git b4a028c4d031

--- y/drivers/net/tun.c
+++ t/drivers/net/tun.c
@@ -281,7 +281,6 @@ static void tun_napi_disable(struct tun_

static void tun_napi_del(struct tun_file *tfile)
{
- if (tfile->napi_enabled)
netif_napi_del(&tfile->napi);
}

--

syzbot

unread,

Jun 23, 2022, 10:48:09 AM6/23/22

to hda...@sina.com, linux-...@vger.kernel.org, syzkall...@googlegroups.com

Hello,

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

netlink: 20 bytes leftover after parsing attributes in process `syz-executor.0'.

==================================================================
BUG: KASAN: use-after-free in free_netdev+0x58c/0x620 net/core/dev.c:10704

Read of size 8 at addr ffff88807ad6e738 by task syz-executor.0/4086

CPU: 0 PID: 4086 Comm: syz-executor.0 Not tainted 5.19.0-rc2-syzkaller-00103-gb4a028c4d031-dirty #0

RIP: 0033:0x7f8631e89109
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:00007f8632f3a168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f8631f9bf60 RCX: 00007f8631e89109

RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000004

RBP: 00007f8631ee305d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffcd4e730bf R14: 00007f8632f3a300 R15: 0000000000022000
</TASK>

Allocated by task 4086:

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:605 [inline]
sk_prot_alloc+0x110/0x290 net/core/sock.c:1975
sk_alloc+0x36/0x770 net/core/sock.c:2028

tun_chr_open+0x7b/0x540 drivers/net/tun.c:3407

misc_open+0x376/0x4a0 drivers/char/misc.c:143
chrdev_open+0x266/0x770 fs/char_dev.c:414
do_dentry_open+0x4a1/0x11f0 fs/open.c:848
do_open fs/namei.c:3520 [inline]
path_openat+0x1c71/0x2910 fs/namei.c:3653
do_filp_open+0x1aa/0x400 fs/namei.c:3680
do_sys_openat2+0x16d/0x4c0 fs/open.c:1278
do_sys_open fs/open.c:1294 [inline]
__do_sys_openat fs/open.c:1310 [inline]
__se_sys_openat fs/open.c:1305 [inline]
__x64_sys_openat+0x13f/0x1f0 fs/open.c:1305
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 4087:

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+0x166/0x1a0 mm/kasan/common.c:328
kasan_slab_free include/linux/kasan.h:200 [inline]
slab_free_hook mm/slub.c:1727 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1753
slab_free mm/slub.c:3507 [inline]
kfree+0xd6/0x4d0 mm/slub.c:4555
sk_prot_free net/core/sock.c:2011 [inline]
__sk_destruct+0x5e5/0x710 net/core/sock.c:2097
sk_destruct net/core/sock.c:2112 [inline]
__sk_free+0x1a4/0x4a0 net/core/sock.c:2123
sk_free+0x78/0xa0 net/core/sock.c:2134
sock_put include/net/sock.h:1927 [inline]

__tun_detach+0xd59/0x1380 drivers/net/tun.c:679
tun_detach drivers/net/tun.c:691 [inline]
tun_chr_close+0x15c/0x180 drivers/net/tun.c:3443

__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 ffff88807ad6e000

which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 1848 bytes inside of

4096-byte region [ffff88807ad6e000, ffff88807ad6f000)

The buggy address belongs to the physical page:

page:ffffea0001eb5a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7ad68
head:ffffea0001eb5a00 order:3 compound_mapcount:0 compound_pincount:0

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

raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888011842140

raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated

prep_new_page mm/page_alloc.c:2456 [inline]
get_page_from_freelist+0x1290/0x3b70 mm/page_alloc.c:4198
__alloc_pages+0x1c7/0x510 mm/page_alloc.c:5426
alloc_pages+0x1aa/0x310 mm/mempolicy.c:2272
alloc_slab_page mm/slub.c:1797 [inline]
allocate_slab+0x26c/0x3c0 mm/slub.c:1942
new_slab mm/slub.c:2002 [inline]
___slab_alloc+0x985/0xd90 mm/slub.c:3002
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3089
slab_alloc_node mm/slub.c:3180 [inline]
slab_alloc mm/slub.c:3222 [inline]
__kmalloc+0x318/0x350 mm/slub.c:4413
kmalloc include/linux/slab.h:605 [inline]
tomoyo_realpath_from_path+0xc3/0x620 security/tomoyo/realpath.c:254
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]

tomoyo_path2_perm+0x264/0x6b0 security/tomoyo/file.c:922
tomoyo_path_rename+0xfe/0x1b0 security/tomoyo/tomoyo.c:287
security_path_rename+0x11d/0x220 security/security.c:1201
do_renameat2+0x472/0xc80 fs/namei.c:4857
__do_sys_rename fs/namei.c:4916 [inline]
__se_sys_rename fs/namei.c:4914 [inline]
__x64_sys_rename+0x7d/0xa0 fs/namei.c:4914

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:1371 [inline]
free_pcp_prepare+0x549/0xd20 mm/page_alloc.c:1421
free_unref_page_prepare mm/page_alloc.c:3343 [inline]
free_unref_page+0x19/0x6a0 mm/page_alloc.c:3438
__unfreeze_partials+0x17c/0x1a0 mm/slub.c:2521
qlink_free mm/kasan/quarantine.c:168 [inline]
qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:187
kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:294
__kasan_slab_alloc+0xa2/0xc0 mm/kasan/common.c:446
kasan_slab_alloc include/linux/kasan.h:224 [inline]
slab_post_alloc_hook mm/slab.h:750 [inline]
slab_alloc_node mm/slub.c:3214 [inline]
slab_alloc mm/slub.c:3222 [inline]
__kmem_cache_alloc_lru mm/slub.c:3229 [inline]

kmem_cache_alloc+0x204/0x3b0 mm/slub.c:3239
getname_flags.part.0+0x50/0x4f0 fs/namei.c:139
getname_flags+0x9a/0xe0 include/linux/audit.h:323
vfs_fstatat+0x73/0xb0 fs/stat.c:254
__do_sys_newfstatat+0x91/0x110 fs/stat.c:425

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

Memory state around the buggy address:

ffff88807ad6e600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807ad6e680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807ad6e700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88807ad6e780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807ad6e800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Tested on:

commit: b4a028c4 ipv4: ping: fix bind address validity check
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git
console output: https://syzkaller.appspot.com/x/log.txt?x=10ea32c4080000

kernel config: https://syzkaller.appspot.com/x/.config?x=70e1a4d352a3c6ae
dashboard link: https://syzkaller.appspot.com/bug?extid=b75c138e9286ac742647
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=1354033ff00000

Hillf Danton

unread,

Jun 24, 2022, 8:44:32 AM6/24/22

to syzbot, linux-...@vger.kernel.org, syzkall...@googlegroups.com

On Tue, 21 Jun 2022 18:01:24 -0700

v1, See if it is due to undeleted tun file.
v2, Avoid adding napi in case of net device that is unregistering.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git b4a028c4d031

--- y/drivers/net/tun.c
+++ t/drivers/net/tun.c

@@ -212,6 +212,7 @@ struct tun_struct {
/* init args */
struct file *file;
struct ifreq *ifr;
+ int all_detached;
};

struct veth {
@@ -701,6 +702,7 @@ static void tun_detach_all(struct net_de
struct tun_file *tfile, *tmp;
int i, n = tun->numqueues;

+ tun->all_detached = 1;
for (i = 0; i < n; i++) {
tfile = rtnl_dereference(tun->tfiles[i]);
BUG_ON(!tfile);
@@ -808,6 +810,10 @@ static int tun_attach(struct tun_struct
if (tfile->detached) {
tun_enable_queue(tfile);
} else {
+ if (tun->all_detached) {
+ err = -EINVAL;
+ goto out;
+ }
sock_hold(&tfile->sk);
tun_napi_init(tun, tfile, napi, napi_frags);
}
@@ -2803,6 +2809,7 @@ static int tun_set_iff(struct net *net,

tun->ifr = ifr;
tun->file = file;
+ tun->all_detached = 0;

tun_net_initialize(dev);

--

syzbot

unread,

Jun 24, 2022, 12:52:10 PM6/24/22

to hda...@sina.com, linux-...@vger.kernel.org, syzkall...@googlegroups.com

Hello,

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

netlink: 20 bytes leftover after parsing attributes in process `syz-executor.0'.

==================================================================
BUG: KASAN: use-after-free in free_netdev+0x58c/0x620 net/core/dev.c:10704

Read of size 8 at addr ffff88807c16c738 by task syz-executor.0/4086

CPU: 0 PID: 4086 Comm: syz-executor.0 Not tainted 5.19.0-rc2-syzkaller-00103-gb4a028c4d031-dirty #0

RIP: 0033:0x7f974fe89109
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:00007f97510d9168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f974ff9bf60 RCX: 00007f974fe89109

RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000004

RBP: 00007f974fee305d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffcf73272af R14: 00007f97510d9300 R15: 0000000000022000
</TASK>

Allocated by task 4086:

tun_chr_open+0x7b/0x540 drivers/net/tun.c:3415

Freed by task 4087:

__tun_detach+0xdb7/0x13e0 drivers/net/tun.c:681
tun_detach drivers/net/tun.c:693 [inline]
tun_chr_close+0x15c/0x180 drivers/net/tun.c:3451

__fput+0x277/0x9d0 fs/file_table.c:317
task_work_run+0xdd/0x1a0 kernel/task_work.c:177

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 ffff88807c16c000

which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 1848 bytes inside of

4096-byte region [ffff88807c16c000, ffff88807c16d000)

The buggy address belongs to the physical page:

page:ffffea0001f05a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7c168
head:ffffea0001f05a00 order:3 compound_mapcount:0 compound_pincount:0

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

raw: 00fff00000010200 ffffea0001f08a00 dead000000000003 ffff888011842140

raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated

qlink_free mm/kasan/quarantine.c:168 [inline]
qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:187
kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:294
__kasan_slab_alloc+0xa2/0xc0 mm/kasan/common.c:446
kasan_slab_alloc include/linux/kasan.h:224 [inline]
slab_post_alloc_hook mm/slab.h:750 [inline]
slab_alloc_node mm/slub.c:3214 [inline]

kmem_cache_alloc_node+0x255/0x3f0 mm/slub.c:3264
__alloc_skb+0x215/0x340 net/core/skbuff.c:414
alloc_skb include/linux/skbuff.h:1426 [inline]
netlink_alloc_large_skb net/netlink/af_netlink.c:1191 [inline]
netlink_sendmsg+0x9a2/0xe10 net/netlink/af_netlink.c:1896

sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:734

__sys_sendto+0x21a/0x320 net/socket.c:2119
__do_sys_sendto net/socket.c:2131 [inline]
__se_sys_sendto net/socket.c:2127 [inline]
__x64_sys_sendto+0xdd/0x1b0 net/socket.c:2127

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

Memory state around the buggy address:

ffff88807c16c600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807c16c680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807c16c700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88807c16c780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807c16c800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Tested on:

commit: b4a028c4 ipv4: ping: fix bind address validity check
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git

console output: https://syzkaller.appspot.com/x/log.txt?x=106d80c0080000

patch: https://syzkaller.appspot.com/x/patch.diff?x=17f803f8080000

Hillf Danton

unread,

Jun 24, 2022, 7:08:06 PM6/24/22

to syzbot, linux-...@vger.kernel.org, syzkall...@googlegroups.com

On Tue, 21 Jun 2022 18:01:24 -0700

v1, See if it is due to undeleted tun file.
v2, Avoid adding napi in case of net device that is unregistering.

v3, delete napi for disabled tun file in tun_detach_all().

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git b4a028c4d031

--- y/drivers/net/tun.c
+++ t/drivers/net/tun.c

@@ -727,6 +727,7 @@ static void tun_detach_all(struct net_de
sock_put(&tfile->sk);
}
list_for_each_entry_safe(tfile, tmp, &tun->disabled, next) {
+ tun_napi_del(tfile);
tun_enable_queue(tfile);
tun_queue_purge(tfile);
xdp_rxq_info_unreg(&tfile->xdp_rxq);
--

syzbot

unread,

Jun 24, 2022, 9:53:10 PM6/24/22

to hda...@sina.com, linux-...@vger.kernel.org, syzkall...@googlegroups.com

Hello,

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

Reported-and-tested-by: syzbot+b75c13...@syzkaller.appspotmail.com

Tested on:

commit: b4a028c4 ipv4: ping: fix bind address validity check
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git

console output: https://syzkaller.appspot.com/x/log.txt?x=15fe514bf00000

patch: https://syzkaller.appspot.com/x/patch.diff?x=175c6e37f00000

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

Reply all

Reply to author

Forward

0 new messages