| 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-2022-49203: drm/amd/display: Fix double free during GPU reset on DC streams |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| drm/amd/display: Fix double free during GPU reset on DC streams |
| |
| [Why] |
| The issue only occurs during the GPU reset code path. |
| |
| We first backup the current state prior to commiting 0 streams |
| internally from DM to DC. This state backup contains valid link |
| encoder assignments. |
| |
| DC will clear the link encoder assignments as part of current state |
| (but not the backup, since it was a copied before the commit) and |
| free the extra stream reference it held. |
| |
| DC requires that the link encoder assignments remain cleared/invalid |
| prior to commiting. Since the backup still has valid assignments we |
| call the interface post reset to clear them. This routine also |
| releases the extra reference that the link encoder interface held - |
| resulting in a double free (and eventually a NULL pointer dereference). |
| |
| [How] |
| We'll have to do a full DC commit anyway after GPU reset because |
| the stream count previously went to 0. |
| |
| We don't need to retain the assignment that we had backed up, so |
| just copy off of the now clean current state assignment after the |
| reset has occcurred with the new link_enc_cfg_copy() interface. |
| |
| The Linux kernel CVE team has assigned CVE-2022-49203 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.17 with commit 6d63fcc2a334f7bd15e4e9b1db50a19335d2af4f and fixed in 5.17.2 with commit bbfcdd6289ba6f00f0cd7d496946dce9f6c600ac |
| Issue introduced in 5.17 with commit 6d63fcc2a334f7bd15e4e9b1db50a19335d2af4f and fixed in 5.18 with commit 32685b32d825ca08c5dec826477332df886c4743 |
| |
| 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-2022-49203 |
| 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/amd/display/amdgpu_dm/amdgpu_dm.c |
| drivers/gpu/drm/amd/display/dc/core/dc_link_enc_cfg.c |
| drivers/gpu/drm/amd/display/dc/inc/link_enc_cfg.h |
| |
| |
| 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/bbfcdd6289ba6f00f0cd7d496946dce9f6c600ac |
| https://git.kernel.org/stable/c/32685b32d825ca08c5dec826477332df886c4743 |
