| 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-2024-58091: drm/fbdev-dma: Add shadow buffering for deferred I/O |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| drm/fbdev-dma: Add shadow buffering for deferred I/O |
| |
| DMA areas are not necessarily backed by struct page, so we cannot |
| rely on it for deferred I/O. Allocate a shadow buffer for drivers |
| that require deferred I/O and use it as framebuffer memory. |
| |
| Fixes driver errors about being "Unable to handle kernel NULL pointer |
| dereference at virtual address" or "Unable to handle kernel paging |
| request at virtual address". |
| |
| The patch splits drm_fbdev_dma_driver_fbdev_probe() in an initial |
| allocation, which creates the DMA-backed buffer object, and a tail |
| that sets up the fbdev data structures. There is a tail function for |
| direct memory mappings and a tail function for deferred I/O with |
| the shadow buffer. |
| |
| It is no longer possible to use deferred I/O without shadow buffer. |
| It can be re-added if there exists a reliably test for usable struct |
| page in the allocated DMA-backed buffer object. |
| |
| The Linux kernel CVE team has assigned CVE-2024-58091 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.11 with commit 5ab91447aa13b8b98bc11f5326f33500b0ee2c48 and fixed in 6.13.6 with commit cdc581169942de3b9e2648cfbd98c5ff9111c2c8 |
| Issue introduced in 6.11 with commit 5ab91447aa13b8b98bc11f5326f33500b0ee2c48 and fixed in 6.14 with commit 3603996432997f7c88da37a97062a46cda01ac9d |
| |
| 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-2024-58091 |
| 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/gpu/drm/drm_fbdev_dma.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/cdc581169942de3b9e2648cfbd98c5ff9111c2c8 |
| https://git.kernel.org/stable/c/3603996432997f7c88da37a97062a46cda01ac9d |
