| 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-2024-56612: mm/gup: handle NULL pages in unpin_user_pages() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| mm/gup: handle NULL pages in unpin_user_pages() |
| |
| The recent addition of "pofs" (pages or folios) handling to gup has a |
| flaw: it assumes that unpin_user_pages() handles NULL pages in the pages** |
| array. That's not the case, as I discovered when I ran on a new |
| configuration on my test machine. |
| |
| Fix this by skipping NULL pages in unpin_user_pages(), just like |
| unpin_folios() already does. |
| |
| Details: when booting on x86 with "numa=fake=2 movablecore=4G" on Linux |
| 6.12, and running this: |
| |
| tools/testing/selftests/mm/gup_longterm |
| |
| ...I get the following crash: |
| |
| BUG: kernel NULL pointer dereference, address: 0000000000000008 |
| RIP: 0010:sanity_check_pinned_pages+0x3a/0x2d0 |
| ... |
| Call Trace: |
| <TASK> |
| ? __die_body+0x66/0xb0 |
| ? page_fault_oops+0x30c/0x3b0 |
| ? do_user_addr_fault+0x6c3/0x720 |
| ? irqentry_enter+0x34/0x60 |
| ? exc_page_fault+0x68/0x100 |
| ? asm_exc_page_fault+0x22/0x30 |
| ? sanity_check_pinned_pages+0x3a/0x2d0 |
| unpin_user_pages+0x24/0xe0 |
| check_and_migrate_movable_pages_or_folios+0x455/0x4b0 |
| __gup_longterm_locked+0x3bf/0x820 |
| ? mmap_read_lock_killable+0x12/0x50 |
| ? __pfx_mmap_read_lock_killable+0x10/0x10 |
| pin_user_pages+0x66/0xa0 |
| gup_test_ioctl+0x358/0xb20 |
| __se_sys_ioctl+0x6b/0xc0 |
| do_syscall_64+0x7b/0x150 |
| entry_SYSCALL_64_after_hwframe+0x76/0x7e |
| |
| The Linux kernel CVE team has assigned CVE-2024-56612 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.12 with commit 94efde1d15399f5c88e576923db9bcd422d217f2 and fixed in 6.12.5 with commit 69d319450d1c651f3b05cd820ff285fdd810c032 |
| Issue introduced in 6.12 with commit 94efde1d15399f5c88e576923db9bcd422d217f2 and fixed in 6.13 with commit a1268be280d8e484ab3606d7476edd0f14bb9961 |
| |
| 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-2024-56612 |
| 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/gup.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/69d319450d1c651f3b05cd820ff285fdd810c032 |
| https://git.kernel.org/stable/c/a1268be280d8e484ab3606d7476edd0f14bb9961 |
