| 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-2023-52486: drm: Don't unref the same fb many times by mistake due to deadlock handling |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| drm: Don't unref the same fb many times by mistake due to deadlock handling |
| |
| If we get a deadlock after the fb lookup in drm_mode_page_flip_ioctl() |
| we proceed to unref the fb and then retry the whole thing from the top. |
| But we forget to reset the fb pointer back to NULL, and so if we then |
| get another error during the retry, before the fb lookup, we proceed |
| the unref the same fb again without having gotten another reference. |
| The end result is that the fb will (eventually) end up being freed |
| while it's still in use. |
| |
| Reset fb to NULL once we've unreffed it to avoid doing it again |
| until we've done another fb lookup. |
| |
| This turned out to be pretty easy to hit on a DG2 when doing async |
| flips (and CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y). The first symptom I |
| saw that drm_closefb() simply got stuck in a busy loop while walking |
| the framebuffer list. Fortunately I was able to convince it to oops |
| instead, and from there it was easier to track down the culprit. |
| |
| The Linux kernel CVE team has assigned CVE-2023-52486 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 4.19.307 with commit 376e21a9e4c2c63ee5d8d3aa74be5082c3882229 |
| Fixed in 5.4.269 with commit 9dd334a8245011ace45e53298175c7b659edb3e7 |
| Fixed in 5.10.210 with commit f55261469be87c55df13db76dc945f6bcd825105 |
| Fixed in 5.15.149 with commit b4af63da9d94986c529d74499fdfe44289acd551 |
| Fixed in 6.1.76 with commit 62f2e79cf9f4f47cc9dea9cebdf58d9f7b5695e0 |
| Fixed in 6.6.15 with commit d7afdf360f4ac142832b098b4de974e867cc063c |
| Fixed in 6.7.3 with commit bfd0feb1b109cb63b87fdcd00122603787c75a1a |
| Fixed in 6.8 with commit cb4daf271302d71a6b9a7c01bd0b6d76febd8f0c |
| |
| 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-2023-52486 |
| 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_plane.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/376e21a9e4c2c63ee5d8d3aa74be5082c3882229 |
| https://git.kernel.org/stable/c/9dd334a8245011ace45e53298175c7b659edb3e7 |
| https://git.kernel.org/stable/c/f55261469be87c55df13db76dc945f6bcd825105 |
| https://git.kernel.org/stable/c/b4af63da9d94986c529d74499fdfe44289acd551 |
| https://git.kernel.org/stable/c/62f2e79cf9f4f47cc9dea9cebdf58d9f7b5695e0 |
| https://git.kernel.org/stable/c/d7afdf360f4ac142832b098b4de974e867cc063c |
| https://git.kernel.org/stable/c/bfd0feb1b109cb63b87fdcd00122603787c75a1a |
| https://git.kernel.org/stable/c/cb4daf271302d71a6b9a7c01bd0b6d76febd8f0c |
