KASAN: use-after-free Read in slip

syzbot

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Nov 21, 2019, 4:19:09 PM11/21/19

to syzkaller...@googlegroups.com

Hello,

syzbot found the following crash on:

HEAD commit: c63ee293 Linux 4.19.85
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=166f836ae00000
kernel config: https://syzkaller.appspot.com/x/.config?x=cbfad1c8058581ad
dashboard link: https://syzkaller.appspot.com/bug?extid=e95c821c30501cc1f5d1
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1456e5cee00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15841902e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e95c82...@syzkaller.appspotmail.com

RDX: 00000000200003c0 RSI: 0000000000005423 RDI: 0000000000000003
RBP: 00007fffb6f4fed0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff
R13: 0000000000000004 R14: 0000000000000000 R15: 0000000000000000
==================================================================
BUG: KASAN: use-after-free in sl_sync drivers/net/slip/slip.c:725 [inline]
BUG: KASAN: use-after-free in slip_open+0xe92/0x1175
drivers/net/slip/slip.c:801
Read of size 8 at addr ffff88809dab5388 by task syz-executor205/7589

CPU: 1 PID: 7589 Comm: syz-executor205 Not tainted 4.19.85-syzkaller #0
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+0x197/0x210 lib/dump_stack.c:118
print_address_description.cold+0x7c/0x20d mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report mm/kasan/report.c:412 [inline]
kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:396
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
sl_sync drivers/net/slip/slip.c:725 [inline]
slip_open+0xe92/0x1175 drivers/net/slip/slip.c:801
tty_ldisc_open.isra.0+0x89/0xd0 drivers/tty/tty_ldisc.c:462
tty_set_ldisc+0x2e3/0x690 drivers/tty/tty_ldisc.c:587
tiocsetd drivers/tty/tty_io.c:2359 [inline]
tty_ioctl+0x65e/0x1510 drivers/tty/tty_io.c:2603
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:501 [inline]
do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:688
ksys_ioctl+0xab/0xd0 fs/ioctl.c:705
__do_sys_ioctl fs/ioctl.c:712 [inline]
__se_sys_ioctl fs/ioctl.c:710 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:710
do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x441199
Code: e8 5c ae 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 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 0f 83 bb 0a fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fffb6f4feb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441199
RDX: 00000000200003c0 RSI: 0000000000005423 RDI: 0000000000000003
RBP: 00007fffb6f4fed0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff
R13: 0000000000000004 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 7588:
save_stack+0x45/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
kasan_kmalloc mm/kasan/kasan.c:553 [inline]
kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:531
__do_kmalloc_node mm/slab.c:3689 [inline]
__kmalloc_node+0x51/0x80 mm/slab.c:3696
kmalloc_node include/linux/slab.h:557 [inline]
kvmalloc_node+0x68/0x100 mm/util.c:423
kvmalloc include/linux/mm.h:577 [inline]
kvzalloc include/linux/mm.h:585 [inline]
alloc_netdev_mqs+0x98/0xd40 net/core/dev.c:8945
sl_alloc drivers/net/slip/slip.c:751 [inline]
slip_open+0x38e/0x1175 drivers/net/slip/slip.c:812
tty_ldisc_open.isra.0+0x89/0xd0 drivers/tty/tty_ldisc.c:462
tty_set_ldisc+0x2e3/0x690 drivers/tty/tty_ldisc.c:587
tiocsetd drivers/tty/tty_io.c:2359 [inline]
tty_ioctl+0x65e/0x1510 drivers/tty/tty_io.c:2603
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:501 [inline]
do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:688
ksys_ioctl+0xab/0xd0 fs/ioctl.c:705
__do_sys_ioctl fs/ioctl.c:712 [inline]
__se_sys_ioctl fs/ioctl.c:710 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:710
do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 7588:
save_stack+0x45/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
__cache_free mm/slab.c:3503 [inline]
kfree+0xcf/0x220 mm/slab.c:3822
kvfree+0x61/0x70 mm/util.c:452
netdev_freemem net/core/dev.c:8899 [inline]
free_netdev+0x384/0x430 net/core/dev.c:9048
slip_open+0xd2a/0x1175 drivers/net/slip/slip.c:858
tty_ldisc_open.isra.0+0x89/0xd0 drivers/tty/tty_ldisc.c:462
tty_set_ldisc+0x2e3/0x690 drivers/tty/tty_ldisc.c:587
tiocsetd drivers/tty/tty_io.c:2359 [inline]
tty_ioctl+0x65e/0x1510 drivers/tty/tty_io.c:2603
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:501 [inline]
do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:688
ksys_ioctl+0xab/0xd0 fs/ioctl.c:705
__do_sys_ioctl fs/ioctl.c:712 [inline]
__se_sys_ioctl fs/ioctl.c:710 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:710
do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88809dab48c0
which belongs to the cache kmalloc-4096 of size 4096
The buggy address is located 2760 bytes inside of
4096-byte region [ffff88809dab48c0, ffff88809dab58c0)
The buggy address belongs to the page:
page:ffffea000276ad00 count:1 mapcount:0 mapping:ffff88812c3f0dc0 index:0x0
compound_mapcount: 0
flags: 0x1fffc0000008100(slab|head)
raw: 01fffc0000008100 ffffea0002657b08 ffffea00027c8e08 ffff88812c3f0dc0
raw: 0000000000000000 ffff88809dab48c0 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88809dab5280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809dab5300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff88809dab5380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88809dab5400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809dab5480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
This bug 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 bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

syzbot

unread,

Nov 25, 2019, 5:33:09 PM11/25/19

to syzkaller...@googlegroups.com

Hello,

syzbot found the following crash on:

HEAD commit: 43598c57 Linux 4.14.156
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=117fa912e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=1a4783d222b56f4
dashboard link: https://syzkaller.appspot.com/bug?extid=beb2bc33804762bfd7cf

compiler: gcc (GCC) 9.0.0 20181231 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=157eceeee00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1784beeee00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:

Reported-by: syzbot+beb2bc...@syzkaller.appspotmail.com

RDX: 0000000020000080 RSI: 0000000000005423 RDI: 0000000000000003
RBP: 00007fff4b945330 R08: 0000000000000001 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff
R13: 0000000000000004 R14: 0000000000000000 R15: 0000000000000000
==================================================================
BUG: KASAN: use-after-free in sl_sync drivers/net/slip/slip.c:725 [inline]

BUG: KASAN: use-after-free in slip_open+0xd14/0xff1
drivers/net/slip/slip.c:805
Read of size 8 at addr ffff88808b6bed48 by task syz-executor221/7018

CPU: 0 PID: 7018 Comm: syz-executor221 Not tainted 4.14.156-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:

__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x142/0x197 lib/dump_stack.c:58
print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252
kasan_report_error mm/kasan/report.c:351 [inline]
kasan_report mm/kasan/report.c:409 [inline]
kasan_report.cold+0xa9/0x2af mm/kasan/report.c:393
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
sl_sync drivers/net/slip/slip.c:725 [inline]
slip_open+0xd14/0xff1 drivers/net/slip/slip.c:805
tty_ldisc_open.isra.0+0x73/0xb0 drivers/tty/tty_ldisc.c:474
tty_set_ldisc+0x29a/0x610 drivers/tty/tty_ldisc.c:599
tiocsetd drivers/tty/tty_io.c:2351 [inline]
tty_ioctl+0x95b/0x1320 drivers/tty/tty_io.c:2595
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x441129
RSP: 002b:00007fff4b945318 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441129
RDX: 0000000020000080 RSI: 0000000000005423 RDI: 0000000000000003
RBP: 00007fff4b945330 R08: 0000000000000001 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff
R13: 0000000000000004 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 7017:
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
save_stack+0x45/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc mm/kasan/kasan.c:551 [inline]
kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529
__do_kmalloc_node mm/slab.c:3682 [inline]
__kmalloc_node+0x51/0x80 mm/slab.c:3689
kmalloc_node include/linux/slab.h:530 [inline]
kvmalloc_node+0x4e/0xe0 mm/util.c:397
kvmalloc include/linux/mm.h:531 [inline]
kvzalloc include/linux/mm.h:539 [inline]
alloc_netdev_mqs+0x7b/0xbc0 net/core/dev.c:8086
sl_alloc drivers/net/slip/slip.c:751 [inline]
slip_open+0x2f1/0xff1 drivers/net/slip/slip.c:816
tty_ldisc_open.isra.0+0x73/0xb0 drivers/tty/tty_ldisc.c:474
tty_set_ldisc+0x29a/0x610 drivers/tty/tty_ldisc.c:599
tiocsetd drivers/tty/tty_io.c:2351 [inline]
tty_ioctl+0x95b/0x1320 drivers/tty/tty_io.c:2595
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 7017:
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
save_stack+0x45/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
__cache_free mm/slab.c:3496 [inline]
kfree+0xcc/0x270 mm/slab.c:3815
kvfree+0x4d/0x60 mm/util.c:416
netdev_freemem net/core/dev.c:8038 [inline]
free_netdev+0x2d0/0x360 net/core/dev.c:8200
slip_open+0xbab/0xff1 drivers/net/slip/slip.c:862
tty_ldisc_open.isra.0+0x73/0xb0 drivers/tty/tty_ldisc.c:474
tty_set_ldisc+0x29a/0x610 drivers/tty/tty_ldisc.c:599
tiocsetd drivers/tty/tty_io.c:2351 [inline]
tty_ioctl+0x95b/0x1320 drivers/tty/tty_io.c:2595
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff88808b6be280

which belongs to the cache kmalloc-4096 of size 4096
The buggy address is located 2760 bytes inside of

4096-byte region [ffff88808b6be280, ffff88808b6bf280)

The buggy address belongs to the page:

page:ffffea00022daf80 count:1 mapcount:0 mapping:ffff88808b6be280 index:0x0

compound_mapcount: 0
flags: 0x1fffc0000008100(slab|head)

raw: 01fffc0000008100 ffff88808b6be280 0000000000000000 0000000100000001
raw: ffffea0002960d20 ffff8880aa801a48 ffff8880aa800dc0 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff88808b6bec00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88808b6bec80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff88808b6bed00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88808b6bed80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88808b6bee00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

syzbot

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Nov 26, 2019, 6:01:02 PM11/26/19

to syzkaller...@googlegroups.com

syzbot has bisected this bug to:

commit 021ede687dcccba48a2cae8c98795e9eedc857e1
Author: Aleksander Morgado <aleks...@aleksander.es>
Date: Wed Nov 13 10:11:10 2019 +0000

net: usb: qmi_wwan: add support for Foxconn T77W968 LTE modules

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15d40496e00000
start commit: 43598c57 Linux 4.14.156
git tree: linux-4.14.y
final crash: https://syzkaller.appspot.com/x/report.txt?x=17d40496e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=13d40496e00000

kernel config: https://syzkaller.appspot.com/x/.config?x=1a4783d222b56f4
dashboard link: https://syzkaller.appspot.com/bug?extid=beb2bc33804762bfd7cf

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=157eceeee00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1784beeee00000

Reported-by: syzbot+beb2bc...@syzkaller.appspotmail.com
Fixes: 021ede687dcc ("net: usb: qmi_wwan: add support for Foxconn T77W968
LTE modules")

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

syzbot

unread,

Nov 26, 2019, 8:37:01 PM11/26/19

to syzkaller...@googlegroups.com

syzbot has bisected this bug to:

commit edc471038b4846b119d0b025f0336bf4b3e1ce23
Author: Jouni Hogander <jouni.h...@unikie.com>
Date: Wed Nov 13 11:45:02 2019 +0000

slip: Fix memory leak in slip_open error path

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=16d7b76ae00000
start commit: c63ee293 Linux 4.19.85
git tree: linux-4.19.y
final crash: https://syzkaller.appspot.com/x/report.txt?x=15d7b76ae00000
console output: https://syzkaller.appspot.com/x/log.txt?x=11d7b76ae00000

kernel config: https://syzkaller.appspot.com/x/.config?x=cbfad1c8058581ad
dashboard link: https://syzkaller.appspot.com/bug?extid=e95c821c30501cc1f5d1

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1456e5cee00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15841902e00000

Reported-by: syzbot+e95c82...@syzkaller.appspotmail.com
Fixes: edc471038b48 ("slip: Fix memory leak in slip_open error path")

syzbot

unread,

Dec 25, 2019, 8:12:02 PM12/25/19

to syzkaller...@googlegroups.com

syzbot suspects this bug was fixed by commit:

commit f5bcc687e3d699bc4949bf37ef5f77fa50269f8c
Author: Jouni Hogander <jouni.h...@unikie.com>
Date: Mon Nov 25 12:23:43 2019 +0000

slip: Fix use-after-free Read in slip_open

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=10efc63ee00000
start commit: 43598c57 Linux 4.14.156
git tree: linux-4.14.y

kernel config: https://syzkaller.appspot.com/x/.config?x=1a4783d222b56f4
dashboard link: https://syzkaller.appspot.com/bug?extid=beb2bc33804762bfd7cf

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=157eceeee00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1784beeee00000

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

#syz fix: slip: Fix use-after-free Read in slip_open