| 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-2024-46838: userfaultfd: don't BUG_ON() if khugepaged yanks our page table |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| userfaultfd: don't BUG_ON() if khugepaged yanks our page table |
| |
| Since khugepaged was changed to allow retracting page tables in file |
| mappings without holding the mmap lock, these BUG_ON()s are wrong - get |
| rid of them. |
| |
| We could also remove the preceding "if (unlikely(...))" block, but then we |
| could reach pte_offset_map_lock() with transhuge pages not just for file |
| mappings but also for anonymous mappings - which would probably be fine |
| but I think is not necessarily expected. |
| |
| The Linux kernel CVE team has assigned CVE-2024-46838 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.6 with commit 1d65b771bc08cd054cf6d3766a72e113dc46d62f and fixed in 6.6.51 with commit 4a594acc12d5954cdc71d4450a386748bf3d136a |
| Issue introduced in 6.6 with commit 1d65b771bc08cd054cf6d3766a72e113dc46d62f and fixed in 6.10.10 with commit db978287e908d48b209e374b00d847b2d785e0a9 |
| Issue introduced in 6.6 with commit 1d65b771bc08cd054cf6d3766a72e113dc46d62f and fixed in 6.11 with commit 4828d207dc5161dc7ddf9a4f6dcfd80c7dd7d20a |
| |
| 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-2024-46838 |
| 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: |
| mm/userfaultfd.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/4a594acc12d5954cdc71d4450a386748bf3d136a |
| https://git.kernel.org/stable/c/db978287e908d48b209e374b00d847b2d785e0a9 |
| https://git.kernel.org/stable/c/4828d207dc5161dc7ddf9a4f6dcfd80c7dd7d20a |
