Summary
In the Linux kernel, the following vulnerability has been resolved: devlink: rate: Unset parent...
In the Linux kernel, the following vulnerability has been resolved:
devlink: rate: Unset parent pointer in devl_rate_nodes_destroy
The function devl_rate_nodes_destroy is documented to "Unset parent for
all rate objects". However, it was only calling the driver-specificrate_leaf_parent_set or rate_node_parent_set ops and decrementing
the parent's refcount, without actually setting thedevlink_rate->parent pointer to NULL.
This leaves a dangling pointer in the devlink_rate struct, which cause
refcount error in netdevsim[1] and mlx5[2]. In addition, this is
inconsistent with the behavior of devlink_nl_rate_parent_node_set,
where the parent pointer is correctly cleared.
This patch fixes the issue by explicitly setting devlink_rate->parent
to NULL after notifying the driver, thus fulfilling the function's
documented behavior for all rate objects.
[1]
repro steps:
echo 1 > /sys/bus/netdevsim/new_device
devlink dev eswitch set netdevsim/netdevsim1 mode switchdev
echo 1 > /sys/bus/netdevsim/devices/netdevsim1/sriov_numvfs
devlink port function rate add netdevsim/netdevsim1/test_node
devlink port function rate set netdevsim/netdevsim1/128 parent test_node
echo 1 > /sys/bus/netdevsim/del_device
dmesg:
refcount_t: decrement hit 0; leaking memory.
WARNING: CPU: 8 PID: 1530 at lib/refcount.c:31 refcount_warn_saturate+0x42/0xe0
CPU: 8 UID: 0 PID: 1530 Comm: bash Not tainted 6.18.0-rc4+ #1 NONE
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
RIP: 0010:refcount_warn_saturate+0x42/0xe0
Call Trace:
devl_rate_leaf_destroy+0x8d/0x90
__nsim_dev_port_del+0x6c/0x70 [netdevsim]
nsim_dev_reload_destroy+0x11c/0x140 [netdevsim]
nsim_drv_remove+0x2b/0xb0 [netdevsim]
device_release_driver_internal+0x194/0x1f0
bus_remove_device+0xc6/0x130
device_del+0x159/0x3c0
device_unregister+0x1a/0x60
del_device_store+0x111/0x170 [netdevsim]
kernfs_fop_write_iter+0x12e/0x1e0
vfs_write+0x215/0x3d0
ksys_write+0x5f/0xd0
do_syscall_64+0x55/0x10f0
entry_SYSCALL_64_after_hwframe+0x4b/0x53
[2]
devlink dev eswitch set pci/0000:08:00.0 mode switchdev
devlink port add pci/0000:08:00.0 flavour pcisf pfnum 0 sfnum 1000
devlink port function rate add pci/0000:08:00.0/group1
devlink port function rate set pci/0000:08:00.0/32768 parent group1
modprobe -r mlx5_ib mlx5_fwctl mlx5_core
dmesg:
refcount_t: decrement hit 0; leaking memory.
WARNING: CPU: 7 PID: 16151 at lib/refcount.c:31 refcount_warn_saturate+0x42/0xe0
CPU: 7 UID: 0 PID: 16151 Comm: bash Not tainted 6.17.0-rc7_for_upstream_min_debug_2025_10_02_12_44 #1 NONE
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
RIP: 0010:refcount_warn_saturate+0x42/0xe0
Call Trace:
devl_rate_leaf_destroy+0x8d/0x90
mlx5_esw_offloads_devlink_port_unregister+0x33/0x60 [mlx5_core]
mlx5_esw_offloads_unload_rep+0x3f/0x50 [mlx5_core]
mlx5_eswitch_unload_sf_vport+0x40/0x90 [mlx5_core]
mlx5_sf_esw_event+0xc4/0x120 [mlx5_core]
notifier_call_chain+0x33/0xa0
blocking_notifier_call_chain+0x3b/0x50
mlx5_eswitch_disable_locked+0x50/0x110 [mlx5_core]
mlx5_eswitch_disable+0x63/0x90 [mlx5_core]
mlx5_unload+0x1d/0x170 [mlx5_core]
mlx5_uninit_one+0xa2/0x130 [mlx5_core]
remove_one+0x78/0xd0 [mlx5_core]
pci_device_remove+0x39/0xa0
device_release_driver_internal+0x194/0x1f0
unbind_store+0x99/0xa0
kernfs_fop_write_iter+0x12e/0x1e0
vfs_write+0x215/0x3d0
ksys_write+0x5f/0xd0
do_syscall_64+0x53/0x1f0
entry_SYSCALL_64_after_hwframe+0x4b/0x53
Impact
The application dereferences a null pointer, causing a crash. Typical impact: denial of service via crash.
CVE-2025-40251 has a CVSS score of 5.5 (Medium). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2025-40251? CVE-2025-40251 is a medium-severity null pointer dereference vulnerability. No fixed version is listed yet. The application dereferences a null pointer, causing a crash.
- How severe is CVE-2025-40251? CVE-2025-40251 has a CVSS score of 5.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Is there a fix for CVE-2025-40251? No fixed version is listed for CVE-2025-40251 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2025-40251 exploitable, and should I be worried? Whether CVE-2025-40251 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-40251 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.