Message-ID: <6aa2b8bc-caa5-44ea-8fd9-18c138a942d3@linaro.org>
Date: Sun, 24 Aug 2025 23:42:26 +0300
From: Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>
To: Johan Hovold <johan@...nel.org>
Cc: Robert Foss <rfoss@...nel.org>, Todor Tomov <todor.too@...il.com>,
 Bryan O'Donoghue <bryan.odonoghue@...aro.org>, linux-media@...r.kernel.org,
 linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: camss NULL-deref on power on with 6.12-rc2

Hi Johan.

On 10/11/24 12:33, Johan Hovold wrote:
> Hi,
> 
> This morning I hit the below NULL-deref in camss when booting a 6.12-rc2
> kernel on the Lenovo ThinkPad X13s.
> 
> I booted the same kernel another 50 times without hitting it again it so
> it may not be a regression, but simply an older, hard to hit bug.
> 
> Hopefully you can figure out what went wrong from just staring at the
> oops and code.
> 
> Johan
> 
> 
> [    5.657860] ov5675 24-0010: failed to get HW configuration: -517
> [    5.676183] vreg_l6q: Bringing 2800000uV into 1800000-1800000uV
> 
> [    6.517689] qcom-camss ac5a000.camss: Adding to iommu group 22
> 
> [    6.589201] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000030
> [    6.589625] Mem abort info:
> [    6.589960]   ESR = 0x0000000096000004
> [    6.590293]   EC = 0x25: DABT (current EL), IL = 32 bits
> [    6.590630]   SET = 0, FnV = 0
> [    6.591619]   EA = 0, S1PTW = 0
> [    6.591968]   FSC = 0x04: level 0 translation fault
> [    6.592298] Data abort info:
> [    6.592621]   ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
> [    6.593112]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
> [    6.593450]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
> [    6.593783] user pgtable: 4k pages, 48-bit VAs, pgdp=000000010daef000
> [    6.594139] [0000000000000030] pgd=0000000000000000, p4d=0000000000000000
> [    6.594214] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
> [    6.594753] Modules linked in: qrtr_mhi cbc des_generic libdes algif_skcipher md5 algif_hash af_alg ip6_tables xt_LOG nf_log_syslog r8152 ipt_REJECT mii nf_reject_ipv4 libphy xt_tcpudp xt_conntrack nf_conntrack libcrc32c nf_defrag_ipv6 nf_defrag_ipv4 iptable_filter qcom_pm8008_regulator ov5675 snd_q6apm(+) hci_uart btqca venus_enc venus_dec bluetooth videobuf2_dma_contig qcom_pm8008 pmic_glink_altmode qcom_spmi_adc5 leds_qcom_lpg qcom_spmi_adc_tm5 mfd_core snd_soc_sc8280xp qcom_spmi_temp_alarm qcom_pon rpmsg_ctrl ecdh_generic fastrpc apr rpmsg_char qrtr_smd qcom_pd_mapper rtc_pm8xxx qcom_battmgr ecc aux_hpd_bridge reboot_mode qcom_vadc_common industrialio nvmem_qcom_spmi_sdam led_class_multicolor regmap_i2c i2c_hid_of_elan snd_soc_qcom_common snd_soc_qcom_sdw pwrseq_qcom_wcn ath11k_pci qcom_camss venus_core videobuf2_dma_sg videobuf2_memops v4l2_mem2mem v4l2_fwnode videobuf2_v4l2 msm v4l2_async videobuf2_common qcom_stats gpio_sbu_mux ath11k videodev drm_exec dispcc_sc8280xp snd_soc_wcd938x phy_qcom_edp gpu_sched
> [    6.594814]  snd_soc_wcd_classh snd_soc_wcd938x_sdw mac80211 drm_display_helper mc snd_soc_lpass_rx_macro snd_soc_lpass_wsa_macro drm_dp_aux_bus snd_soc_lpass_tx_macro snd_soc_lpass_va_macro camcc_sc8280xp regmap_sdw videocc_sm8350 i2c_qcom_cci soundwire_qcom snd_soc_wcd_mbhc libarc4 snd_soc_lpass_macro_common phy_qcom_qmp_combo cfg80211 qcom_q6v5_pas llcc_qcom aux_bridge snd_soc_core snd_compress qcom_pil_info rfkill qcom_common snd_pcm qcom_glink_smem pci_pwrctl_pwrseq drm_kms_helper pci_pwrctl_core mhi typec qcom_glink pwrseq_core icc_bwmon snd_timer phy_qcom_qmp_usb qrtr phy_qcom_snps_femto_v2 qcom_q6v5 gpucc_sc8280xp pinctrl_sc8280xp_lpass_lpi snd qcom_sysmon pinctrl_lpass_lpi lpasscc_sc8280xp pmic_glink soundcore mdt_loader pdr_interface soundwire_bus qcom_rng rpmsg_core leds_gpio input_leds qcom_pdr_msg socinfo qmi_helpers rng_core qcom_wdt pwm_bl icc_osm_l3 led_class fuse dm_mod ip_tables x_tables ipv6 autofs4 pcie_qcom crc8 phy_qcom_qmp_pcie nvme nvme_core hid_multitouch i2c_qcom_geni i2c_hid_of i2c_hid drm
> [    6.594866]  i2c_core
> [    6.594868] CPU: 0 UID: 0 PID: 557 Comm: v4l_id Not tainted 6.12.0-rc2 #165
> [    6.594871] Hardware name: LENOVO 21BYZ9SRUS/21BYZ9SRUS, BIOS N3HET87W (1.59 ) 12/05/2023
> [    6.594872] pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [    6.594874] pc : camss_find_sensor+0x20/0x74 [qcom_camss]
> [    6.594885] lr : camss_get_pixel_clock+0x18/0x60 [qcom_camss]
> [    6.594889] sp : ffff800082d538f0
> [    6.594890] x29: ffff800082d538f0 x28: ffff800082d53c70 x27: ffff670cc0404618
> [    6.594893] x26: 0000000000000000 x25: 0000000000000000 x24: ffff670cd33173d0
> [    6.594895] x23: ffff800082d539a8 x22: ffff670cd33192c8 x21: ffff800082d539b8
> [    6.594898] x20: 0000000000000002 x19: 0000000000020001 x18: 0000000000000000
> [    6.594900] x17: 0000000000000000 x16: ffffbf0bffbecdd0 x15: 0000000000000001
> [    6.594902] x14: ffff670cc5c95300 x13: ffff670cc0b38980 x12: ffff670cc5c95ba8
> [    6.594905] x11: ffffbf0c00f73000 x10: 0000000000000000 x9 : 0000000000000000
> [    6.594907] x8 : ffffbf0c0085d000 x7 : 0000000000000000 x6 : 0000000000000078
> [    6.594910] x5 : 0000000000000000 x4 : ffff670cd3318598 x3 : ffff670cd3318468
> [    6.594912] x2 : ffff670cd3317728 x1 : ffff800082d539b8 x0 : 0000000000000000
> [    6.594915] Call trace:
> [    6.594915]  camss_find_sensor+0x20/0x74 [qcom_camss]
> [    6.594920]  camss_get_pixel_clock+0x18/0x60 [qcom_camss]
> [    6.594924]  vfe_get+0xb8/0x504 [qcom_camss]
> [    6.594931]  vfe_set_power+0x30/0x58 [qcom_camss]
> [    6.594936]  pipeline_pm_power_one+0x13c/0x150 [videodev]
> [    6.594951]  pipeline_pm_power.part.0+0x58/0xf4 [videodev]
> [    6.594960]  v4l2_pipeline_pm_use+0x58/0x94 [videodev]
> [    6.594969]  v4l2_pipeline_pm_get+0x14/0x20 [videodev]
> [    6.594978]  video_open+0x78/0xf4 [qcom_camss]
> [    6.594982]  v4l2_open+0x80/0x120 [videodev]

As you remember the problem has been discussed in the past [1], for
your information the issue has been indirectly fixed in v6.17-rc1 by
getting rid of v4l2_pipeline_pm_get() from .open, see commit
164202f68203 ("media: qcom: camss: Power pipeline only when streaming").

Still the old race is left unresolved, and it could lead to a NULL
pointer dereference, but practically it would be close to impossible to
reproduce it, since one more step of starting a video stream is needed.

> [    6.594991]  chrdev_open+0xb4/0x204
> [    6.594996]  do_dentry_open+0x138/0x4d0
> [    6.595000]  vfs_open+0x2c/0xe4
> [    6.595003]  path_openat+0x2b4/0x9fc
> [    6.595005]  do_filp_open+0x80/0x130
> [    6.595007]  do_sys_openat2+0xb4/0xe8
> [    6.595010]  __arm64_sys_openat+0x64/0xac
> [    6.595012]  invoke_syscall+0x48/0x110
> [    6.595016]  el0_svc_common.constprop.0+0xc0/0xe0
> [    6.595018]  do_el0_svc+0x1c/0x28
> [    6.595021]  el0_svc+0x48/0x114
> [    6.595023]  el0t_64_sync_handler+0xc0/0xc4
> [    6.595025]  el0t_64_sync+0x190/0x194
> [    6.595028] Code: 52800033 72a00053 d503201f f9402400 (f9401801)
> [    6.595029] ---[ end trace 0000000000000000 ]---

[1] https://lore.kernel.org/all/aE_hlGHkRZqFFacR@hovoldconsulting.com/

-- 
Best wishes,
Vladimir

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