KMSAN: uninit-value in ath9k_htc_rx_msg

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ce8056d1 wip: changed copy_from_user where instrumented
git tree: https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=130c562c900000
kernel config: https://syzkaller.appspot.com/x/.config?x=3afe005fb99591f
dashboard link: https://syzkaller.appspot.com/bug?extid=2ca247c2d60c7023de7f
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
userspace arch: i386

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+2ca247...@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in ath9k_htc_rx_msg+0x28f/0x1f50 drivers/net/wireless/ath/ath9k/htc_hst.c:410
CPU: 0 PID: 4867 Comm: systemd-udevd Not tainted 5.8.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x21c/0x280 lib/dump_stack.c:118
kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:121
__msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
ath9k_htc_rx_msg+0x28f/0x1f50 drivers/net/wireless/ath/ath9k/htc_hst.c:410
ath9k_hif_usb_rx_stream drivers/net/wireless/ath/ath9k/hif_usb.c:638 [inline]
ath9k_hif_usb_rx_cb+0x1841/0x1d10 drivers/net/wireless/ath/ath9k/hif_usb.c:671
__usb_hcd_giveback_urb+0x687/0x870 drivers/usb/core/hcd.c:1650
usb_hcd_giveback_urb+0x1cb/0x730 drivers/usb/core/hcd.c:1716
dummy_timer+0xd98/0x71c0 drivers/usb/gadget/udc/dummy_hcd.c:1967
call_timer_fn+0x226/0x550 kernel/time/timer.c:1404
expire_timers+0x4fc/0x780 kernel/time/timer.c:1449
__run_timers+0xaf4/0xd30 kernel/time/timer.c:1773
run_timer_softirq+0x2d/0x50 kernel/time/timer.c:1786
__do_softirq+0x2ea/0x7f5 kernel/softirq.c:293
asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711
</IRQ>
__run_on_irqstack arch/x86/include/asm/irq_stack.h:23 [inline]
run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:50 [inline]
do_softirq_own_stack+0x7c/0xa0 arch/x86/kernel/irq_64.c:77
invoke_softirq kernel/softirq.c:390 [inline]
__irq_exit_rcu+0x226/0x270 kernel/softirq.c:420
irq_exit_rcu+0xe/0x10 kernel/softirq.c:432
sysvec_apic_timer_interrupt+0x107/0x130 arch/x86/kernel/apic/apic.c:1091
asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:593
RIP: 0010:tomoyo_path_matches_pattern+0xba/0x4d0 security/tomoyo/util.c:920
Code: 48 89 45 a0 8b 02 89 45 d0 4d 85 f6 4c 8b ad 70 ff ff ff 0f 85 c6 01 00 00 4c 89 7d b8 41 0f b7 44 24 0c 48 89 45 80 48 89 df <e8> 71 fd ea fc 49 8d 5c 24 0f 0f b7 00 48 89 45 88 8b 02 89 45 a8
RSP: 0018:ffff888111c0f858 EFLAGS: 00000246
RAX: 0000000000000015 RBX: ffff888111d41fe4 RCX: 0000000111941fd8
RDX: ffff888111941fd8 RSI: 0000000000000440 RDI: ffff888111d41fe4
RBP: ffff888111c0f8e8 R08: ffffea000000000f R09: ffff88812fffa000
R10: 0000000000000003 R11: ffff88811a320000 R12: ffff888111d41fd8
R13: ffff88811a3209d8 R14: 0000000000000000 R15: ffff888111c0fab0
tomoyo_compare_name_union security/tomoyo/file.c:87 [inline]
tomoyo_check_path_acl+0x272/0x360 security/tomoyo/file.c:260
tomoyo_check_acl+0x239/0x5a0 security/tomoyo/domain.c:175
tomoyo_path_permission security/tomoyo/file.c:586 [inline]
tomoyo_path_perm+0x83f/0xc60 security/tomoyo/file.c:838
tomoyo_inode_getattr+0x54/0x60 security/tomoyo/tomoyo.c:123
security_inode_getattr+0x144/0x280 security/security.c:1278
vfs_getattr fs/stat.c:121 [inline]
vfs_statx+0x34c/0x940 fs/stat.c:206
vfs_lstat include/linux/fs.h:3302 [inline]
__do_sys_newlstat fs/stat.c:374 [inline]
__se_sys_newlstat+0xce/0x920 fs/stat.c:368
__x64_sys_newlstat+0x3e/0x60 fs/stat.c:368
do_syscall_64+0xad/0x160 arch/x86/entry/common.c:386
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f72dd774335
Code: Bad RIP value.
RSP: 002b:00007ffeb28263b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000006
RAX: ffffffffffffffda RBX: 000055a2c06613f0 RCX: 00007f72dd774335
RDX: 00007ffeb28263f0 RSI: 00007ffeb28263f0 RDI: 000055a2c06603f0
RBP: 00007ffeb28264b0 R08: 00007f72dda33178 R09: 0000000000001010
R10: 0000000000000020 R11: 0000000000000246 R12: 000055a2c06603f0
R13: 000055a2c0660410 R14: 000055a2c064ce5b R15: 000055a2c064ce60

Uninit was created at:
kmsan_save_stack_with_flags+0x3c/0x90 mm/kmsan/kmsan.c:144
kmsan_internal_alloc_meta_for_pages mm/kmsan/kmsan_shadow.c:269 [inline]
kmsan_alloc_page+0xc5/0x1a0 mm/kmsan/kmsan_shadow.c:293
__alloc_pages_nodemask+0xdf0/0x1030 mm/page_alloc.c:4889
__alloc_pages include/linux/gfp.h:509 [inline]
__alloc_pages_node include/linux/gfp.h:522 [inline]
alloc_pages_node include/linux/gfp.h:536 [inline]
__page_frag_cache_refill mm/page_alloc.c:4964 [inline]
page_frag_alloc+0x35b/0x880 mm/page_alloc.c:4994
__netdev_alloc_skb+0x2a8/0xc90 net/core/skbuff.c:451
__dev_alloc_skb include/linux/skbuff.h:2813 [inline]
ath9k_hif_usb_rx_stream drivers/net/wireless/ath/ath9k/hif_usb.c:620 [inline]
ath9k_hif_usb_rx_cb+0xe5a/0x1d10 drivers/net/wireless/ath/ath9k/hif_usb.c:671
__usb_hcd_giveback_urb+0x687/0x870 drivers/usb/core/hcd.c:1650
usb_hcd_giveback_urb+0x1cb/0x730 drivers/usb/core/hcd.c:1716
dummy_timer+0xd98/0x71c0 drivers/usb/gadget/udc/dummy_hcd.c:1967
call_timer_fn+0x226/0x550 kernel/time/timer.c:1404
expire_timers+0x4fc/0x780 kernel/time/timer.c:1449
__run_timers+0xaf4/0xd30 kernel/time/timer.c:1773
run_timer_softirq+0x2d/0x50 kernel/time/timer.c:1786
__do_softirq+0x2ea/0x7f5 kernel/softirq.c:293
=====================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: ce8056d1 wip: changed copy_from_user where instrumented
git tree: https://github.com/google/kmsan.git master

console output: https://syzkaller.appspot.com/x/log.txt?x=12985a16900000

kernel config: https://syzkaller.appspot.com/x/.config?x=3afe005fb99591f
dashboard link: https://syzkaller.appspot.com/bug?extid=2ca247c2d60c7023de7f
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1468efe2900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10bb9fba900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2ca247...@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in ath9k_htc_rx_msg+0x28f/0x1f50 drivers/net/wireless/ath/ath9k/htc_hst.c:410

CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.8.0-rc5-syzkaller #0

RIP: 0010:native_irq_disable arch/x86/include/asm/irqflags.h:49 [inline]
RIP: 0010:arch_local_irq_disable arch/x86/include/asm/irqflags.h:89 [inline]
RIP: 0010:acpi_safe_halt drivers/acpi/processor_idle.c:112 [inline]
RIP: 0010:acpi_idle_do_entry drivers/acpi/processor_idle.c:525 [inline]
RIP: 0010:acpi_idle_enter+0x817/0xeb0 drivers/acpi/processor_idle.c:651
Code: 85 db 74 0a f7 d3 44 21 fb 48 85 db 74 32 4d 85 ff 75 3a 48 8b 5d a0 e9 0c 00 00 00 e8 12 b2 78 fb 0f 00 2d 25 15 1c 0b fb f4 <fa> eb 5a 84 c0 8b 7d 90 0f 45 7d 94 e8 d8 9a f4 fb e9 74 fc ff ff
RSP: 0018:ffff88812df93bc8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff8881dfefce70 RCX: 000000012db88000
RDX: ffff88812df88000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff88812df93ca0 R08: ffffffff86420acc R09: ffff88812fffa000
R10: 0000000000000002 R11: ffff88812df88000 R12: ffff88812df889d8
R13: ffff8881dfefcc64 R14: 0000000000000000 R15: 0000000000000000
cpuidle_enter_state+0x860/0x12b0 drivers/cpuidle/cpuidle.c:235
cpuidle_enter+0xe3/0x170 drivers/cpuidle/cpuidle.c:346
call_cpuidle kernel/sched/idle.c:126 [inline]
cpuidle_idle_call kernel/sched/idle.c:214 [inline]
do_idle+0x668/0x810 kernel/sched/idle.c:276
cpu_startup_entry+0x45/0x50 kernel/sched/idle.c:372
start_secondary+0x1bf/0x240 arch/x86/kernel/smpboot.c:268
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243

[Alexander Potapenko]

This bug bites us quite often on syzbot: https://syzkaller.appspot.com/bug?id=659ddf411502a2fe220c8f9be696d5a8d8db726e (17k crashes)

The patch below by ph...@philpotter.co.uk (https://syzkaller.appspot.com/text?tag=Patch&x=173dcb51d00000) seems to fix the problem, but I have no idea what's going on there.

==============================================================

diff --git a/drivers/net/wireless/ath/ath9k/htc_hst.c b/drivers/net/wireless/ath/ath9k/htc_hst.c
index 510e61e97dbc..9dbfff7a388e 100644
--- a/drivers/net/wireless/ath/ath9k/htc_hst.c
+++ b/drivers/net/wireless/ath/ath9k/htc_hst.c
@@ -403,7 +403,7 @@ void ath9k_htc_rx_msg(struct htc_target *htc_handle,
     struct htc_endpoint *endpoint;
     __be16 *msg_id;
 
-    if (!htc_handle || !skb)
+    if (!htc_handle || !skb || !pskb_may_pull(skb, sizeof(struct htc_frame_hdr)))
         return;
 
     htc_hdr = (struct htc_frame_hdr *) skb->data;

==============================================================

[Alexander Potapenko]

(adding back people originally CCed on the syzkaller bug.
Unfortunately it isn't possible to reply to all in Google Groups)

--
Alexander Potapenko
Software Engineer

Google Germany GmbH
Erika-Mann-Straße, 33
80636 München

Geschäftsführer: Paul Manicle, Liana Sebastian
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg

[Tetsuo Handa]

Hello.

I found that your patch was applied. But since the reproducer tested only 0 byte
case, I think that rejecting only less than sizeof(struct htc_frame_hdr) bytes
is not sufficient.

More complete patch with Ack from Toke is waiting at
https://lkml.kernel.org/r/7acfa1be-4b5c-b2ce...@I-love.SAKURA.ne.jp .

Please consider overriding with my version.

On 2022/08/24 22:30, Alexander Potapenko wrote:
> (adding back people originally CCed on the syzkaller bug.
> Unfortunately it isn't possible to reply to all in Google Groups)
>

[Alexander Potapenko]

On Thu, Aug 25, 2022 at 4:34 PM Tetsuo Handa
<penguin...@i-love.sakura.ne.jp> wrote:
>
> Hello.
Hi Tetsuo,

> I found that your patch was applied. But since the reproducer tested only 0 byte
> case, I think that rejecting only less than sizeof(struct htc_frame_hdr) bytes
> is not sufficient.
>
> More complete patch with Ack from Toke is waiting at
> https://lkml.kernel.org/r/7acfa1be-4b5c-b2ce...@I-love.SAKURA.ne.jp .

Thanks for letting me know! I just checked that your patch indeed
fixes the issue I am facing.
If it is more complete, I think we'd indeed better use yours.

[Toke Høiland-Jørgensen]

FWIW, that patch is just waiting for Kalle to apply it, and I just
noticed this whole thread has used his old email address, so updating
that now as a gentle ping :)

-Toke

[Tetsuo Handa]

I recognized that "ath9k: fix an uninit value use in ath9k_htc_rx_msg()" is
local to KMSAN tree.
https://github.com/google/kmsan/commit/d891e35583bf2e81ccc7a2ea548bf7cf47329f40

That patch needs to be dropped, for I confirmed that passing pad_len == 8 below
still triggers uninit value at ath9k_htc_fw_panic_report(). (My patch does not
trigger at ath9k_htc_fw_panic_report().)

fd = syz_usb_connect_ath9k(3, 0x5a, 0x20000800, 0);
*(uint16_t*)0x20000880 = 0 + pad_len;
*(uint16_t*)0x20000882 = 0x4e00;
memmove((uint8_t*)0x20000884, "\x99\x11\x22\x33\x00\x00\x00\x00\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF", 16);
syz_usb_ep_write(fd, 0x82, 4 + pad_len, 0x20000880);



Also, that patch has a skb leak bug; according to comment for ath9k_htc_rx_msg()

* Service messages (Data, WMI) passed to the corresponding
* endpoint RX handlers, which have to free the SKB.

, I think that this function is supposed to free skb if skb != NULL.

If dev_kfree_skb_any(skb) needs to be used when epid is invalid and pipe_id != USB_REG_IN_PIPE,
why it is OK to use kfree_skb(skb) if epid == 0x99 and pipe_id != USB_REG_IN_PIPE ?

We don't call kfree_skb(skb) if 0 < epid < ENDPOINT_MAX and endpoint->ep_callbacks.rx == NULL.
Why it is OK not to call kfree_skb(skb) in that case?

Callers can't pass such combinations? I leave these questions to ath9k developers...

[Alexander Potapenko]

On Fri, Aug 26, 2022 at 3:35 AM Tetsuo Handa
<penguin...@i-love.sakura.ne.jp> wrote:
>
> On 2022/08/26 0:09, Alexander Potapenko wrote:
> > On Thu, Aug 25, 2022 at 4:34 PM Tetsuo Handa
> > <penguin...@i-love.sakura.ne.jp> wrote:
> >>
> >> Hello.
> > Hi Tetsuo,
> >
> >> I found that your patch was applied. But since the reproducer tested only 0 byte
> >> case, I think that rejecting only less than sizeof(struct htc_frame_hdr) bytes
> >> is not sufficient.
> >>
> >> More complete patch with Ack from Toke is waiting at
> >> https://lkml.kernel.org/r/7acfa1be-4b5c-b2ce...@I-love.SAKURA.ne.jp .
> >
> > Thanks for letting me know! I just checked that your patch indeed
> > fixes the issue I am facing.
> > If it is more complete, I think we'd indeed better use yours.
>
> I recognized that "ath9k: fix an uninit value use in ath9k_htc_rx_msg()" is
> local to KMSAN tree.
> https://github.com/google/kmsan/commit/d891e35583bf2e81ccc7a2ea548bf7cf47329f40

I actually did a rebase of KMSAN tree to v6.0-rc2 yesterday and
dropped that patch (picked yours instead).
Thanks for the heads-up!

[Phillip Potter]

Hi Tetsuo,

Thank you for this improved patch. My original one was somewhat naive
attempt at a resolution.

Regards,
Phil

[Kalle Valo]

I was on vacation but back now, I'll start processing patches soon.

--
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches