| 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-2025-21655: io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period |
| |
| io_eventfd_do_signal() is invoked from an RCU callback, but when |
| dropping the reference to the io_ev_fd, it calls io_eventfd_free() |
| directly if the refcount drops to zero. This isn't correct, as any |
| potential freeing of the io_ev_fd should be deferred another RCU grace |
| period. |
| |
| Just call io_eventfd_put() rather than open-code the dec-and-test and |
| free, which will correctly defer it another RCU grace period. |
| |
| The Linux kernel CVE team has assigned CVE-2025-21655 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.1 with commit 21a091b970cdbcf3e8ff829234b51be6f9192766 and fixed in 6.1.125 with commit 6b63308c28987c6010b1180c72a6db4df6c68033 |
| Issue introduced in 6.1 with commit 21a091b970cdbcf3e8ff829234b51be6f9192766 and fixed in 6.6.72 with commit 8efff2aa2d95dc437ab67c5b4a9f1d3f367baa10 |
| Issue introduced in 6.1 with commit 21a091b970cdbcf3e8ff829234b51be6f9192766 and fixed in 6.12.10 with commit a7085c3ae43b86d4b3d1b8275e6a67f14257e3b7 |
| Issue introduced in 6.1 with commit 21a091b970cdbcf3e8ff829234b51be6f9192766 and fixed in 6.13 with commit c9a40292a44e78f71258b8522655bffaf5753bdb |
| |
| 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-2025-21655 |
| 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: |
| io_uring/eventfd.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/6b63308c28987c6010b1180c72a6db4df6c68033 |
| https://git.kernel.org/stable/c/8efff2aa2d95dc437ab67c5b4a9f1d3f367baa10 |
| https://git.kernel.org/stable/c/a7085c3ae43b86d4b3d1b8275e6a67f14257e3b7 |
| https://git.kernel.org/stable/c/c9a40292a44e78f71258b8522655bffaf5753bdb |
| https://project-zero.issues.chromium.org/issues/388499293 |
