| 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-2024-56678: powerpc/mm/fault: Fix kfence page fault reporting |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| powerpc/mm/fault: Fix kfence page fault reporting |
| |
| copy_from_kernel_nofault() can be called when doing read of /proc/kcore. |
| /proc/kcore can have some unmapped kfence objects which when read via |
| copy_from_kernel_nofault() can cause page faults. Since *_nofault() |
| functions define their own fixup table for handling fault, use that |
| instead of asking kfence to handle such faults. |
| |
| Hence we search the exception tables for the nip which generated the |
| fault. If there is an entry then we let the fixup table handler handle the |
| page fault by returning an error from within ___do_page_fault(). |
| |
| This can be easily triggered if someone tries to do dd from /proc/kcore. |
| eg. dd if=/proc/kcore of=/dev/null bs=1M |
| |
| Some example false negatives: |
| |
| =============================== |
| BUG: KFENCE: invalid read in copy_from_kernel_nofault+0x9c/0x1a0 |
| Invalid read at 0xc0000000fdff0000: |
| copy_from_kernel_nofault+0x9c/0x1a0 |
| 0xc00000000665f950 |
| read_kcore_iter+0x57c/0xa04 |
| proc_reg_read_iter+0xe4/0x16c |
| vfs_read+0x320/0x3ec |
| ksys_read+0x90/0x154 |
| system_call_exception+0x120/0x310 |
| system_call_vectored_common+0x15c/0x2ec |
| |
| BUG: KFENCE: use-after-free read in copy_from_kernel_nofault+0x9c/0x1a0 |
| Use-after-free read at 0xc0000000fe050000 (in kfence-#2): |
| copy_from_kernel_nofault+0x9c/0x1a0 |
| 0xc00000000665f950 |
| read_kcore_iter+0x57c/0xa04 |
| proc_reg_read_iter+0xe4/0x16c |
| vfs_read+0x320/0x3ec |
| ksys_read+0x90/0x154 |
| system_call_exception+0x120/0x310 |
| system_call_vectored_common+0x15c/0x2ec |
| |
| The Linux kernel CVE team has assigned CVE-2024-56678 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.13 with commit 90cbac0e995dd92f7bcf82f74aa50250bf194a4a and fixed in 5.15.174 with commit e0a470b5733c1fe068d5c58b0bb91ad539604bc6 |
| Issue introduced in 5.13 with commit 90cbac0e995dd92f7bcf82f74aa50250bf194a4a and fixed in 6.1.120 with commit 4d2655754e94741b159aa807b72ea85518a65fd5 |
| Issue introduced in 5.13 with commit 90cbac0e995dd92f7bcf82f74aa50250bf194a4a and fixed in 6.6.64 with commit 9ea8d8bf9b625e8ad3be6b0432aecdc549914121 |
| Issue introduced in 5.13 with commit 90cbac0e995dd92f7bcf82f74aa50250bf194a4a and fixed in 6.11.11 with commit 7eaeb7a49b6d16640f9f3c9074c05175d74c710b |
| Issue introduced in 5.13 with commit 90cbac0e995dd92f7bcf82f74aa50250bf194a4a and fixed in 6.12.2 with commit 15f78d2c3d1452645bd8b9da909b0ca266f83c43 |
| Issue introduced in 5.13 with commit 90cbac0e995dd92f7bcf82f74aa50250bf194a4a and fixed in 6.13 with commit 06dbbb4d5f7126b6307ab807cbf04ecfc459b933 |
| |
| 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-2024-56678 |
| 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: |
| arch/powerpc/mm/fault.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/e0a470b5733c1fe068d5c58b0bb91ad539604bc6 |
| https://git.kernel.org/stable/c/4d2655754e94741b159aa807b72ea85518a65fd5 |
| https://git.kernel.org/stable/c/9ea8d8bf9b625e8ad3be6b0432aecdc549914121 |
| https://git.kernel.org/stable/c/7eaeb7a49b6d16640f9f3c9074c05175d74c710b |
| https://git.kernel.org/stable/c/15f78d2c3d1452645bd8b9da909b0ca266f83c43 |
| https://git.kernel.org/stable/c/06dbbb4d5f7126b6307ab807cbf04ecfc459b933 |
