CVE-2024-40910
In the Linux kernel, the following vulnerability has been resolved: ax25: Fix refcount imbalance on inbound connections When releasing a socket in ax25_release(), we call netdev_put() to decrease the refcount on the associated ax.25 device.
Does this matter?
Lower severity and a low EPSS score (0.45%). Track it; it rarely justifies an emergency change on its own.
Description
In the Linux kernel, the following vulnerability has been resolved: ax25: Fix refcount imbalance on inbound connections When releasing a socket in ax25_release(), we call netdev_put() to decrease the refcount on the associated ax.25 device. However, the execution path for accepting an incoming connection never calls netdev_hold(). This imbalance leads to refcount errors, and ultimately to kernel crashes. A typical call trace for the above situation will start with one of the following errors: refcount_t: decrement hit 0; leaking memory. refcount_t: underflow; use-after-free. And will then have a trace like: Call Trace: <TASK> ? show_regs+0x64/0x70 ? __warn+0x83/0x120 ? refcount_warn_saturate+0xb2/0x100 ? report_bug+0x158/0x190 ? prb_read_valid+0x20/0x30 ? handle_bug+0x3e/0x70 ? exc_invalid_op+0x1c/0x70 ? asm_exc_invalid_op+0x1f/0x30 ? refcount_warn_saturate+0xb2/0x100 ? refcount_warn_saturate+0xb2/0x100 ax25_release+0x2ad/0x360 __sock_release+0x35/0xa0 sock_close+0x19/0x20 [...] On reboot (or any attempt to remove the interface), the kernel gets stuck in an infinite loop: unregister_netdevice: waiting for ax0 to become free. Usage count = 0 This patch corrects these issues by ensuring that we call netdev_hold() and ax25_dev_hold() for new connections in ax25_accept(). This makes the logic leading to ax25_accept() match the logic for ax25_bind(): in both cases we increment the refcount, which is ultimately decremented in ax25_release().
- CVSS 3.1
- 5.5 MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.45% probability · 38th percentile
- CISA KEV
- Not listed
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/3c34fb0bd4a4237592c5ecb5b2e2531900c55774Patch
- https://git.kernel.org/stable/c/52100fd74ad07b53a4666feafff1cd11436362d3Patch
- https://git.kernel.org/stable/c/a723a6c8d4831cc8e2c7b0c9f3f0c010d4671964Patch
- https://git.kernel.org/stable/c/f4df9d6c8d4e4c818252b0419c2165d66eabd4ebPatch
- https://git.kernel.org/stable/c/3c34fb0bd4a4237592c5ecb5b2e2531900c55774Patch
- https://git.kernel.org/stable/c/52100fd74ad07b53a4666feafff1cd11436362d3Patch
- https://git.kernel.org/stable/c/a723a6c8d4831cc8e2c7b0c9f3f0c010d4671964Patch
- https://git.kernel.org/stable/c/f4df9d6c8d4e4c818252b0419c2165d66eabd4ebPatch
- https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.