| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2024-40910: ax25: Fix refcount imbalance on inbound connections |
| |
| 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(). |
| |
| The Linux kernel CVE team has assigned CVE-2024-40910 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.18 with commit 9fd75b66b8f68498454d685dc4ba13192ae069b0 and fixed in 6.1.95 with commit f4df9d6c8d4e4c818252b0419c2165d66eabd4eb |
| Issue introduced in 5.18 with commit 9fd75b66b8f68498454d685dc4ba13192ae069b0 and fixed in 6.6.35 with commit 52100fd74ad07b53a4666feafff1cd11436362d3 |
| Issue introduced in 5.18 with commit 9fd75b66b8f68498454d685dc4ba13192ae069b0 and fixed in 6.9.6 with commit a723a6c8d4831cc8e2c7b0c9f3f0c010d4671964 |
| Issue introduced in 5.18 with commit 9fd75b66b8f68498454d685dc4ba13192ae069b0 and fixed in 6.10 with commit 3c34fb0bd4a4237592c5ecb5b2e2531900c55774 |
| Issue introduced in 4.14.277 with commit c44a453ffe16eb08acdc6129ac4fa0192dbc0456 |
| Issue introduced in 4.19.240 with commit de55a1338e6a48ff1e41ea8db1432496fbe2a62b |
| Issue introduced in 5.4.190 with commit 9e1e088a57c23251f1cfe9601bbd90ade2ea73b9 |
| Issue introduced in 5.10.112 with commit b20a5ab0f5fb175750c6bafd4cf12daccf00c738 |
| Issue introduced in 5.15.35 with commit 452ae92b99062d2f6a34324eaf705a3b7eac9f8b |
| Issue introduced in 5.17.2 with commit 534156dd4ed768e30a43de0036f45dca7c54818f |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2024-40910 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| net/ax25/af_ax25.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/f4df9d6c8d4e4c818252b0419c2165d66eabd4eb |
| https://git.kernel.org/stable/c/52100fd74ad07b53a4666feafff1cd11436362d3 |
| https://git.kernel.org/stable/c/a723a6c8d4831cc8e2c7b0c9f3f0c010d4671964 |
| https://git.kernel.org/stable/c/3c34fb0bd4a4237592c5ecb5b2e2531900c55774 |
