| 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-2024-35985: sched/eevdf: Prevent vlag from going out of bounds in reweight_eevdf() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| sched/eevdf: Prevent vlag from going out of bounds in reweight_eevdf() |
| |
| It was possible to have pick_eevdf() return NULL, which then causes a |
| NULL-deref. This turned out to be due to entity_eligible() returning |
| falsely negative because of a s64 multiplcation overflow. |
| |
| Specifically, reweight_eevdf() computes the vlag without considering |
| the limit placed upon vlag as update_entity_lag() does, and then the |
| scaling multiplication (remember that weight is 20bit fixed point) can |
| overflow. This then leads to the new vruntime being weird which then |
| causes the above entity_eligible() to go side-ways and claim nothing |
| is eligible. |
| |
| Thus limit the range of vlag accordingly. |
| |
| All this was quite rare, but fatal when it does happen. |
| |
| The Linux kernel CVE team has assigned CVE-2024-35985 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.6.4 with commit 14204acc09f652169baed1141c671429047b1313 and fixed in 6.6.30 with commit 470d347b14b0ecffa9b39cf8f644fa2351db3efb |
| Issue introduced in 6.7 with commit eab03c23c2a162085b13200d7942fc5a00b5ccc8 and fixed in 6.8.9 with commit 06f27e6d7bf0abf54488259ef36bbf0e1fccb35c |
| Issue introduced in 6.7 with commit eab03c23c2a162085b13200d7942fc5a00b5ccc8 and fixed in 6.9 with commit 1560d1f6eb6b398bddd80c16676776c0325fe5fe |
| |
| 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-2024-35985 |
| 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: |
| kernel/sched/fair.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/470d347b14b0ecffa9b39cf8f644fa2351db3efb |
| https://git.kernel.org/stable/c/06f27e6d7bf0abf54488259ef36bbf0e1fccb35c |
| https://git.kernel.org/stable/c/1560d1f6eb6b398bddd80c16676776c0325fe5fe |
