Look up another CVE · open CVE-2025-21801 in the interactive tracker
CVE-2025-21801
net: ravb: Fix missing rtnl lock in suspend/resume path
Published 2025-02-27 (20 months ago) by the Linux kernel CNA. Subsystem drivers/net. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2025-21801 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | fixed | 6.12.13-1 | Update the kernel and reboot. Fixed in 6.12.13-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 6.12.13-1 | Update the kernel and reboot. Fixed in 6.12.13-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 6.12.13-1 | Update the kernel and reboot. Fixed in 6.12.13-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Fix the suspend/resume path by ensuring the rtnl lock is held where required. Calls to ravb_open, ravb_close and wol operations must be performed under the rtnl lock to prevent conflicts with ongoing ndo operations. Without this fix, the following warning is triggered: [ 39.032969] ============================= [ 39.032983] WARNING: suspicious RCU usage [ 39.033019] ----------------------------- [ 39.033033] drivers/net/phy/phy_device.c:2004 suspicious rcu_dereference_protected() usage! ... [ 39.033597] stack backtrace: [ 39.033613] CPU: 0 UID: 0 PID: 174 Comm: python3 Not tainted 6.13.0-rc7-next-20250116-arm64-renesas-00002-g35245dfdc62c #7 [ 39.033623] Hardware name: Renesas SMARC EVK version 2 based on r9a08g045s33 (DT) [ 39.033628] Call trace: [ 39.033633] show_stack+0x14/0x1c (C) [ 39.033652] dump_stack_lvl+0xb4/0xc4 [ 39.033664] dump_stack+0x14/0x1c [ 39.033671] lockdep_rcu_suspicious+0x16c/0x22c [ 39.033682] phy_detach+0x160/0x190 [ 39.033694] phy_disconnect+0x40/0x54 [ 39.033703] ravb_close+0x6c/0x1cc [ 39.033714] ravb_suspend+0x48/0x120 [ 39.033721] dpm_run_callback+0x4c/0x14c [ 39.033731] device_suspend+0x11c/0x4dc [ 39.033740] dpm_suspend+0xdc/0x214 [ 39.033748] dpm_suspend_start+0x48/0x60 [ 39.033758] suspend_devices_and_enter+0x124/0x574 [ 39.033769] pm_suspend+0x1ac/0x274 [ 39.033778] state_store+0x88/0x124 [ 39.033788] kobj_attr_store+0x14/0x24 [ 39.033798] sysfs_kf_write+0x48/0x6c [ 39.033808] kernfs_fop_write_iter+0x118/0x1a8 [ 39.033817] vfs_write+0x27c/0x378 [ 39.033825] ksys_write+0x64/0xf4 [ 39.033833] __arm64_sys_write+0x18/0x20 [ 39.033841] invoke_syscall+0x44/0x104 [ 39.033852] el0_svc_common.constprop.0+0xb4/0xd4 [ 39.033862] do_el0_svc+0x18/0x20 [ 39.033870] el0_svc+0x3c/0xf0 [ 39.033880] el0t_64_sync_handler+0xc0/0xc4 [ 39.033888] el0t_64_sync+0x154/0x158 [ 39.041274] ravb 11c30000.ethernet eth0: Link is Down
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/net/ethernet/renesas/ravb_main.c
- What this is
- RENESAS ETHERNET AVB DRIVERMAINTAINERS section matched on drivers/net/ethernet/renesas/ravb* · netdev@vger.kernel.org · Maintained
- Kernel module
- ravb
Check it on the machine
grep -wE 'CONFIG_ETHERNET|CONFIG_NET_VENDOR_RENESAS|CONFIG_RAVB' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w ravbPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian does not build this code in 2 releases. It does build it in 2 releases, so the answer depends on which release the machine runs.
- bookworm, trixien
- forky, sidMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt-amd64, arm64/cloud-arm64, armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- n
- not enabled on any flavour - this release does not build the code
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_ETHERNET, CONFIG_NET_VENDOR_RENESAS, CONFIG_RAVB
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2025-02-27 (20 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.20%, higher than 9.2% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/net
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.9 | 6.12.13 | 0296981941cf |
| 4.9 | 6.13.2 | ad19522c007b |
| 4.9 | 6.14 | 2c2ebb2b4957 |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- The vulnerable code is a platform Ethernet driver's PM callback pair reached only through local activity — a suspend/resume transition plus a concurrent local rtnl-protected operation (ethtool ioctl, netlink, or an internally scheduled work item). No remote peer can reach or drive the unlocked window.
- AC:LAttack complexity, low
- The attacker influences both sides: suspend/resume cycles are continuously and automatically driven on these Renesas embedded/automotive targets (and requestable by an unprivileged local session on general-purpose systems), while unprivileged ethtool/ioctl calls and interface traffic supply the concurrent rtnl-side operation, and the attempt can be repeated indefinitely until it lands.
- PR:LPrivileges required, low
- An unprivileged local user suffices — `ETHTOOL_GSET`/`GLINKSETTINGS`/`GSTATS` are explicitly exempt from any capability check yet still run under `rtnl_lock()`, and generating the traffic that arms `ravb_tx_timeout_work()` needs only an ordinary socket; no root or `CAP_NET_ADMIN` is required.
- UI:NUser interaction, none
- System suspend/resume is triggered automatically by autosleep, idle timeouts, or RTC wakeups on the affected embedded and automotive platforms, so no victim action is needed for the window to open.
- S:UScope, unchanged
- The corruption is confined to kernel heap and DMA-coherent memory managed by the same kernel security authority; no VM, IOMMU, or sandbox boundary is crossed.
- C:HConfidentiality impact, high
- The unlocked teardown frees the `phy_device` and the descriptor rings while concurrent rtnl holders still hold pointers to them, and use-after-free of these objects lets an attacker who reclaims the freed slabs read back kernel memory contents through the surviving accessors.
- I:HIntegrity impact, high
- Concurrent `ravb_ring_free()` from suspend and `ravb_tx_timeout_work()` double-frees DMA-coherent rings, page-pool objects, and kmalloc'd arrays, and the DMAC can remain programmed to write into freed pages — heap corruption plus a device-driven write primitive suitable for control-flow hijacking.
- A:HAvailability impact, high
- The race reliably produces kernel crashes — double `dma_free_coherent`/`page_pool_destroy`, use-after-free oopses on the detached PHY, and external aborts from MMIO access to an AVB block whose reset is asserted and clocks gated — taking down the system's primary network interface and the machine itself.