| 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-2024-39479: drm/i915/hwmon: Get rid of devm |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| drm/i915/hwmon: Get rid of devm |
| |
| When both hwmon and hwmon drvdata (on which hwmon depends) are device |
| managed resources, the expectation, on device unbind, is that hwmon will be |
| released before drvdata. However, in i915 there are two separate code |
| paths, which both release either drvdata or hwmon and either can be |
| released before the other. These code paths (for device unbind) are as |
| follows (see also the bug referenced below): |
| |
| Call Trace: |
| release_nodes+0x11/0x70 |
| devres_release_group+0xb2/0x110 |
| component_unbind_all+0x8d/0xa0 |
| component_del+0xa5/0x140 |
| intel_pxp_tee_component_fini+0x29/0x40 [i915] |
| intel_pxp_fini+0x33/0x80 [i915] |
| i915_driver_remove+0x4c/0x120 [i915] |
| i915_pci_remove+0x19/0x30 [i915] |
| pci_device_remove+0x32/0xa0 |
| device_release_driver_internal+0x19c/0x200 |
| unbind_store+0x9c/0xb0 |
| |
| and |
| |
| Call Trace: |
| release_nodes+0x11/0x70 |
| devres_release_all+0x8a/0xc0 |
| device_unbind_cleanup+0x9/0x70 |
| device_release_driver_internal+0x1c1/0x200 |
| unbind_store+0x9c/0xb0 |
| |
| This means that in i915, if use devm, we cannot gurantee that hwmon will |
| always be released before drvdata. Which means that we have a uaf if hwmon |
| sysfs is accessed when drvdata has been released but hwmon hasn't. |
| |
| The only way out of this seems to be do get rid of devm_ and release/free |
| everything explicitly during device unbind. |
| |
| v2: Change commit message and other minor code changes |
| v3: Cleanup from i915_hwmon_register on error (Armin Wolf) |
| v4: Eliminate potential static analyzer warning (Rodrigo) |
| Eliminate fetch_and_zero (Jani) |
| v5: Restore previous logic for ddat_gt->hwmon_dev error return (Andi) |
| |
| The Linux kernel CVE team has assigned CVE-2024-39479 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 6.6.34 with commit cfa73607eb21a4ce1d6294a2c5733628897b48a2 |
| Fixed in 6.9.5 with commit ce5a22d22db691d14516c3b8fdbf69139eb2ea8f |
| Fixed in 6.10 with commit 5bc9de065b8bb9b8dd8799ecb4592d0403b54281 |
| |
| 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-2024-39479 |
| 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/i915/i915_hwmon.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/cfa73607eb21a4ce1d6294a2c5733628897b48a2 |
| https://git.kernel.org/stable/c/ce5a22d22db691d14516c3b8fdbf69139eb2ea8f |
| https://git.kernel.org/stable/c/5bc9de065b8bb9b8dd8799ecb4592d0403b54281 |
