| 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-2024-44976: ata: pata_macio: Fix DMA table overflow |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| ata: pata_macio: Fix DMA table overflow |
| |
| Kolbjørn and Jonáš reported that their 32-bit PowerMacs were crashing |
| in pata-macio since commit 09fe2bfa6b83 ("ata: pata_macio: Fix |
| max_segment_size with PAGE_SIZE == 64K"). |
| |
| For example: |
| |
| kernel BUG at drivers/ata/pata_macio.c:544! |
| Oops: Exception in kernel mode, sig: 5 [#1] |
| BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=2 DEBUG_PAGEALLOC PowerMac |
| ... |
| NIP pata_macio_qc_prep+0xf4/0x190 |
| LR pata_macio_qc_prep+0xfc/0x190 |
| Call Trace: |
| 0xc1421660 (unreliable) |
| ata_qc_issue+0x14c/0x2d4 |
| __ata_scsi_queuecmd+0x200/0x53c |
| ata_scsi_queuecmd+0x50/0xe0 |
| scsi_queue_rq+0x788/0xb1c |
| __blk_mq_issue_directly+0x58/0xf4 |
| blk_mq_plug_issue_direct+0x8c/0x1b4 |
| blk_mq_flush_plug_list.part.0+0x584/0x5e0 |
| __blk_flush_plug+0xf8/0x194 |
| __submit_bio+0x1b8/0x2e0 |
| submit_bio_noacct_nocheck+0x230/0x304 |
| btrfs_work_helper+0x200/0x338 |
| process_one_work+0x1a8/0x338 |
| worker_thread+0x364/0x4c0 |
| kthread+0x100/0x104 |
| start_kernel_thread+0x10/0x14 |
| |
| That commit increased max_segment_size to 64KB, with the justification |
| that the SCSI core was already using that size when PAGE_SIZE == 64KB, |
| and that there was existing logic to split over-sized requests. |
| |
| However with a sufficiently large request, the splitting logic causes |
| each sg to be split into two commands in the DMA table, leading to |
| overflow of the DMA table, triggering the BUG_ON(). |
| |
| With default settings the bug doesn't trigger, because the request size |
| is limited by max_sectors_kb == 1280, however max_sectors_kb can be |
| increased, and apparently some distros do that by default using udev |
| rules. |
| |
| Fix the bug for 4KB kernels by reverting to the old max_segment_size. |
| |
| For 64KB kernels the sg_tablesize needs to be halved, to allow for the |
| possibility that each sg will be split into two. |
| |
| The Linux kernel CVE team has assigned CVE-2024-44976 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.10 with commit 09fe2bfa6b83f865126ce3964744863f69a4a030 and fixed in 6.10.7 with commit 709e4c8f78e156ab332297bdd87527ec3da4e2d4 |
| Issue introduced in 6.10 with commit 09fe2bfa6b83f865126ce3964744863f69a4a030 and fixed in 6.11 with commit 822c8020aebcf5804a143b891e34f29873fee5e2 |
| |
| 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-2024-44976 |
| 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/ata/pata_macio.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/709e4c8f78e156ab332297bdd87527ec3da4e2d4 |
| https://git.kernel.org/stable/c/822c8020aebcf5804a143b891e34f29873fee5e2 |
