| 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-2025-21704: usb: cdc-acm: Check control transfer buffer size before access |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| usb: cdc-acm: Check control transfer buffer size before access |
| |
| If the first fragment is shorter than struct usb_cdc_notification, we can't |
| calculate an expected_size. Log an error and discard the notification |
| instead of reading lengths from memory outside the received data, which can |
| lead to memory corruption when the expected_size decreases between |
| fragments, causing `expected_size - acm->nb_index` to wrap. |
| |
| This issue has been present since the beginning of git history; however, |
| it only leads to memory corruption since commit ea2583529cd1 |
| ("cdc-acm: reassemble fragmented notifications"). |
| |
| A mitigating factor is that acm_ctrl_irq() can only execute after userspace |
| has opened /dev/ttyACM*; but if ModemManager is running, ModemManager will |
| do that automatically depending on the USB device's vendor/product IDs and |
| its other interfaces. |
| |
| The Linux kernel CVE team has assigned CVE-2025-21704 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 5.4.291 with commit a4e1ae5c0533964170197e4fb4f33bc8c1db5cd2 |
| Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 5.10.235 with commit 90dd2f1b7342b9a671a5ea4160f408037b92b118 |
| Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 5.15.179 with commit 871619c2b78fdfe05afb4e8ba548678687beb812 |
| Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.1.129 with commit 7828e9363ac4d23b02419bf2a45b9f1d9fb35646 |
| Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.6.79 with commit 6abb510251e75f875797d8983a830e6731fa281c |
| Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.12.16 with commit f64079bef6a8a7823358c3f352ea29a617844636 |
| Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.13.4 with commit 383d516a0ebc8641372b521c8cb717f0f1834831 |
| Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.14 with commit e563b01208f4d1f609bcab13333b6c0e24ce6a01 |
| |
| 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-2025-21704 |
| 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: |
| drivers/usb/class/cdc-acm.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/a4e1ae5c0533964170197e4fb4f33bc8c1db5cd2 |
| https://git.kernel.org/stable/c/90dd2f1b7342b9a671a5ea4160f408037b92b118 |
| https://git.kernel.org/stable/c/871619c2b78fdfe05afb4e8ba548678687beb812 |
| https://git.kernel.org/stable/c/7828e9363ac4d23b02419bf2a45b9f1d9fb35646 |
| https://git.kernel.org/stable/c/6abb510251e75f875797d8983a830e6731fa281c |
| https://git.kernel.org/stable/c/f64079bef6a8a7823358c3f352ea29a617844636 |
| https://git.kernel.org/stable/c/383d516a0ebc8641372b521c8cb717f0f1834831 |
| https://git.kernel.org/stable/c/e563b01208f4d1f609bcab13333b6c0e24ce6a01 |
| https://project-zero.issues.chromium.org/issues/395107243 |
