On 11/4/2024 9:08 PM, Johan Hovold wrote:
On Mon, Nov 04, 2024 at 04:26:15PM -0800, Chris Lew wrote:
On 11/1/2024 8:01 AM, Johan Hovold wrote:
[ 8.825593] Unable to handle kernel NULL pointer dereference at virtual
address 0000000000000034
.
[ 9.002030] CPU: 10 UID: 0 PID: 11 Comm: kworker/u48:0 Not tainted 6.12.0-rc5 #4
[ 9.029550] Hardware name: Qualcomm CRD, BIOS 6.0.231221.BOOT.MXF.2.4-00348.1-HAMOA-1 12/21/2023
[ 9.029552] Workqueue: qrtr_ns_handler qrtr_ns_worker [qrtr]
[ 9.061350] pstate: a1400005 (NzCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
[ 9.061353] pc : mhi_gen_tre+0x44/0x224 [mhi]
[ 9.106931] lr : mhi_gen_tre+0x40/0x224 [mhi]
[ 9.106934] sp : ffff8000800fb7d0
[ 9.106935] x29: ffff8000800fb7d0 x28: ffff6db7852bd000 x27: ffff800082490188
[ 9.120382] dwc3 a000000.usb: Adding to iommu group 5
[ 9.133750]
[ 9.133752] x26: 0000000000000000 x25: ffff6db783e65080 x24: ffff80008248ff88
[ 9.133754] x23: 0000000000000000 x22: ffff80008248ff80 x21: ffff8000800fb890
[ 9.133756] x20: 0000000000000000 x19: 0000000000000002 x18: 000000000005cf20
[ 9.133758] x17: 0000000000000028 x16: 0000000000000000
[ 9.172738] x15: ffffa5834131fbd0
[ 9.172741] x14: ffffa5834137caf0 x13: 000000000000ce30 x12: ffff6db7808bc028
[ 9.172743] x11: ffffa58341993000 x10: 0000000000000000 x9 : 00000000cf3f2b90
[ 9.172745] x8 : 0000000094e5072b x7 : 00000000000404ce x6 : ffffa5834162cfb0
[ 9.172747] x5 : 000000000000008b x4 : ffffa583419cddf0 x3 : 0000000000000007
[ 9.172750] x2 : 0000000000000000
[ 9.192697] x1 : 000000000000000a x0 : ffff6db7808bb700
[ 9.192700] Call trace:
[ 9.192701] mhi_gen_tre+0x44/0x224 [mhi]
[ 9.192704] mhi_queue+0x74/0x194 [mhi]
[ 9.192706] mhi_queue_skb+0x5c/0x8c [mhi]
[ 9.210985] qcom_mhi_qrtr_send+0x6c/0x160 [qrtr_mhi]
[ 9.210989] qrtr_node_enqueue+0xd0/0x4a0 [qrtr]
[ 9.210992] qrtr_bcast_enqueue+0x78/0xe8 [qrtr]
[ 9.225530] qrtr_sendmsg+0x15c/0x33c [qrtr]
[ 9.225532] sock_sendmsg+0xc0/0xec
[ 9.240436] kernel_sendmsg+0x30/0x40
[ 9.240438] service_announce_new+0xbc/0x1c4 [qrtr]
[ 9.240440] qrtr_ns_worker+0x714/0x794 [qrtr]
[ 9.240441] process_one_work+0x210/0x614
[ 9.254527] worker_thread+0x23c/0x378
[ 9.254529] kthread+0x124/0x128
[ 9.254531] ret_from_fork+0x10/0x20
[ 9.254534] Code: aa0003f9 aa1b03e0 94001a4d f9401b14 (3940d280)
[ 9.267369] ---[ end trace 0000000000000000 ]---
[ 9.267371] Kernel panic - not syncing: Oops: Fatal exception in interrupt
Thanks for reporting this.
Thanks for taking a look, Chris.
I'm not sure the in-kernel pd-mapper should be affecting this path. I
think this is for WLAN since it is the mhi qrtr and I'm not aware of
WLAN needing to listen to the pd-mapper framework.
This function is called for both the WWAN and WLAN on this machine, and
it seems like the modem is typically probed first and around the time
when I saw the NULL-deref.
[ 8.802728] mhi-pci-generic 0005:01:00.0: mhi_gen_tre - buf_info = ffff800080d75000, offsetof(buf_info->used) = 0x34
...
[ 9.980638] ath12k_pci 0004:01:00.0: mhi_gen_tre - buf_info = ffff800081d35000, offsetof(buf_info->used) = 0x34
The offset seems to be mapped back to
linux/drivers/bus/mhi/host/main.c:1220, I had some extra debug configs
enabled so not sure the offset is still valid.
WARN_ON(buf_info->used);
buf_info->pre_mapped = info->pre_mapped;
This looks like the null pointer would happen if qrtr tried to send
before mhi_channel_prepare() is called.
I didn't look closely at the code, but I can confirm that the offset of
buf_info->used is indeed 0x34, which could indicate that it's the
buf_info = buf_ring->wp;
pointer that was NULL.
I think we have a patch that might fix this, let me dig it up and send
it out.
Would that patch still help?
https://lore.kernel.org/lkml/20241104-qrtr_mhi-v1-1-79adf7e3bba5@xxxxxxxxxxx/
Yea this is the exact patch I had in mind, didnt realize the patch was
already sent a while back.
I naively tried adding a sleep after registering the endpoint, but that
is at least not sufficient to trigger the NULL-deref.
Looking at the callstack, this is broadcasting a NEW_SERVER notification
from qrtr_ns. I think you can force this by starting and stopping some
qmi service with the added sleep. Do you have tqftpserv or diag-router
in your environment? Those will open qmi services, so starting and
stopping those will cause the new_server broadcast in qrtr_ns.
Johan
