CVE-2025-38136 usb: renesas_usbhs: Reorder clock handling and power management in probe
A flaw in the Renesas USBHS driver causes a kernel crash during probe due to uninitialized clock access, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-38136?
CVE-2025-38136 is a medium-severity vulnerability in Debian Debian Linux, published on 3 Jul 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
usb: renesas_usbhs: Reorder clock handling and power management in probe
Reorder the initialization sequence in `usbhs_probe()` to enable runtime PM before accessing registers, preventing potential crashes due to uninitialized clocks.
Currently, in the probe path, registers are accessed before enabling the clocks, leading to a synchronous external abort on the RZ/V2H SoC. The problematic call flow is as follows:
usbhs_probe() usbhs_sys_clock_ctrl() usbhs_bset() usbhs_write() iowrite16() <-- Register access before enabling clocks
Since `iowrite16()` is performed without ensuring the required clocks are enabled, this can lead to access errors. To fix this, enable PM runtime early in the probe function and ensure clocks are acquired before register access, preventing crashes like the following on RZ/V2H:
[13.272640] Internal error: synchronous external abort: 0000000096000010 [#1] PREEMPT SMP [13.280814] Modules linked in: cec renesas_usbhs(+) drm_kms_helper fuse drm backlight ipv6 [13.289088] CPU: 1 UID: 0 PID: 195 Comm: (udev-worker) Not tainted 6.14.0-rc7+ #98 [13.296640] Hardware name: Renesas RZ/V2H EVK Board based on r9a09g057h44 (DT) [13.303834] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) [13.310770] pc : usbhs_bset+0x14/0x4c [renesas_usbhs] [13.315831] lr : usbhs_probe+0x2e4/0x5ac [renesas_usbhs] [13.321138] sp : ffff8000827e3850 [13.324438] x29: ffff8000827e3860 x28: 0000000000000000 x27: ffff8000827e3ca0 [13.331554] x26: ffff8000827e3ba0 x25: ffff800081729668 x24: 0000000000000025 [13.338670] x23: ffff0000c0f08000 x22: 0000000000000000 x21: ffff0000c0f08010 [13.345783] x20: 0000000000000000 x19: ffff0000c3b52080 x18: 00000000ffffffff [13.352895] x17: 0000000000000000 x16: 0000000000000000 x15: ffff8000827e36ce [13.360009] x14: 00000000000003d7 x13: 00000000000003d7 x12: 0000000000000000 [13.367122] x11: 0000000000000000 x10: 0000000000000aa0 x9 : ffff8000827e3750 [13.374235] x8 : ffff0000c1850b00 x7 : 0000000003826060 x6 : 000000000000001c [13.381347] x5 : 000000030d5fcc00 x4 : ffff8000825c0000 x3 : 0000000000000000 [13.388459] x2 : 0000000000000400 x1 : 0000000000000000 x0 : ffff0000c3b52080 [13.395574] Call trace: [13.398013] usbhs_bset+0x14/0x4c [renesas_usbhs] (P) [13.403076] platform_probe+0x68/0xdc [13.406738] really_probe+0xbc/0x2c0 [13.410306] __driver_probe_device+0x78/0x120 [13.414653] driver_probe_device+0x3c/0x154 [13.418825] __driver_attach+0x90/0x1a0 [13.422647] bus_for_each_dev+0x7c/0xe0 [13.426470] driver_attach+0x24/0x30 [13.430032] bus_add_driver+0xe4/0x208 [13.433766] driver_register+0x68/0x130 [13.437587] __platform_driver_register+0x24/0x30 [13.442273] renesas_usbhs_driver_init+0x20/0x1000 [renesas_usbhs] [13.448450] do_one_initcall+0x60/0x1d4 [13.452276] do_init_module+0x54/0x1f8 [13.456014] load_module+0x1754/0x1c98 [13.459750] init_module_from_file+0x88/0xcc [13.464004] __arm64_sys_finit_module+0x1c4/0x328 [13.468689] invoke_syscall+0x48/0x104 [13.472426] el0_svc_common.constprop.0+0xc0/0xe0 [13.477113] do_el0_svc+0x1c/0x28 [13.480415] el0_svc+0x30/0xcc [13.483460] el0t_64_sync_handler+0x10c/0x138 [13.487800] el0t_64_sync+0x198/0x19c [13.491453] Code: 2a0103e1 12003c42 12003c63 8b010084 (79400084) [13.497522] ---[ end trace 0000000000000000 ]---
Weakness: CWE-908
Which versions are affected by CVE-2025-38136?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-38136?
Apply the vendor's patch.
Is CVE-2025-38136 being exploited?
There is no known exploitation of CVE-2025-38136 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-64601, BELL-CVE-2025-38136, DEBIAN-CVE-2025-38136, GHSA-4xq6-m26v-vqpr, ROOT-OS-DEBIAN-11-CVE-2025-38136, ROOT-OS-DEBIAN-12-CVE-2025-38136 and 3 more.