| 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-2024-38580: epoll: be better about file lifetimes |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| epoll: be better about file lifetimes |
| |
| epoll can call out to vfs_poll() with a file pointer that may race with |
| the last 'fput()'. That would make f_count go down to zero, and while |
| the ep->mtx locking means that the resulting file pointer tear-down will |
| be blocked until the poll returns, it means that f_count is already |
| dead, and any use of it won't actually get a reference to the file any |
| more: it's dead regardless. |
| |
| Make sure we have a valid ref on the file pointer before we call down to |
| vfs_poll() from the epoll routines. |
| |
| The Linux kernel CVE team has assigned CVE-2024-38580 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 5.15.161 with commit cbfd1088e24ec4c1199756a37cb8e4cd0a4b016e |
| Fixed in 6.1.93 with commit 559214eb4e5c3d05e69428af2fae2691ba1eb784 |
| Fixed in 6.6.33 with commit 4f65f4defe4e23659275ce5153541cd4f76ce2d2 |
| Fixed in 6.8.12 with commit 16e3182f6322575eb7c12e728ad3c7986a189d5d |
| Fixed in 6.9 with commit 4efaa5acf0a1d2b5947f98abb3acf8bfd966422b |
| |
| 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-2024-38580 |
| 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: |
| fs/eventpoll.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/cbfd1088e24ec4c1199756a37cb8e4cd0a4b016e |
| https://git.kernel.org/stable/c/559214eb4e5c3d05e69428af2fae2691ba1eb784 |
| https://git.kernel.org/stable/c/4f65f4defe4e23659275ce5153541cd4f76ce2d2 |
| https://git.kernel.org/stable/c/16e3182f6322575eb7c12e728ad3c7986a189d5d |
| https://git.kernel.org/stable/c/4efaa5acf0a1d2b5947f98abb3acf8bfd966422b |
