| 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-2022-48762: arm64: extable: fix load_unaligned_zeropad() reg indices |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| arm64: extable: fix load_unaligned_zeropad() reg indices |
| |
| In ex_handler_load_unaligned_zeropad() we erroneously extract the data and |
| addr register indices from ex->type rather than ex->data. As ex->type will |
| contain EX_TYPE_LOAD_UNALIGNED_ZEROPAD (i.e. 4): |
| * We'll always treat X0 as the address register, since EX_DATA_REG_ADDR is |
| extracted from bits [9:5]. Thus, we may attempt to dereference an |
| arbitrary address as X0 may hold an arbitrary value. |
| * We'll always treat X4 as the data register, since EX_DATA_REG_DATA is |
| extracted from bits [4:0]. Thus we will corrupt X4 and cause arbitrary |
| behaviour within load_unaligned_zeropad() and its caller. |
| |
| Fix this by extracting both values from ex->data as originally intended. |
| |
| On an MTE-enabled QEMU image we are hitting the following crash: |
| Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 |
| Call trace: |
| fixup_exception+0xc4/0x108 |
| __do_kernel_fault+0x3c/0x268 |
| do_tag_check_fault+0x3c/0x104 |
| do_mem_abort+0x44/0xf4 |
| el1_abort+0x40/0x64 |
| el1h_64_sync_handler+0x60/0xa0 |
| el1h_64_sync+0x7c/0x80 |
| link_path_walk+0x150/0x344 |
| path_openat+0xa0/0x7dc |
| do_filp_open+0xb8/0x168 |
| do_sys_openat2+0x88/0x17c |
| __arm64_sys_openat+0x74/0xa0 |
| invoke_syscall+0x48/0x148 |
| el0_svc_common+0xb8/0xf8 |
| do_el0_svc+0x28/0x88 |
| el0_svc+0x24/0x84 |
| el0t_64_sync_handler+0x88/0xec |
| el0t_64_sync+0x1b4/0x1b8 |
| Code: f8695a69 71007d1f 540000e0 927df12a (f940014a) |
| |
| The Linux kernel CVE team has assigned CVE-2022-48762 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.16 with commit 753b32368705c396000f95f33c3b7018474e33ad and fixed in 5.16.5 with commit 47fe7a1c5e3e011eeb4ab79f2d54a794fdd1c3eb |
| Issue introduced in 5.16 with commit 753b32368705c396000f95f33c3b7018474e33ad and fixed in 5.17 with commit 3758a6c74e08bdc15ccccd6872a6ad37d165239a |
| |
| 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-2022-48762 |
| 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/arm64/mm/extable.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/47fe7a1c5e3e011eeb4ab79f2d54a794fdd1c3eb |
| https://git.kernel.org/stable/c/3758a6c74e08bdc15ccccd6872a6ad37d165239a |
