CVE-2024-50022
Description
In the Linux kernel, the following vulnerability has been resolved: device-dax: correct pgoff align in dax_set_mapping() pgoff should be aligned using ALIGN_DOWN() instead of ALIGN(). Otherwise, vmf->address not aligned to fault_size will be aligned to the next alignment, that can result in memory failure getting the wrong address. It's a subtle situation that only can be observed in page_mapped_in_vma() after the page is page fault handled by dev_dax_huge_fault. Generally, there is little chance to perform page_mapped_in_vma in dev-dax's page unless in specific error injection to the dax device to trigger an MCE - memory-failure. In that case, page_mapped_in_vma() will be triggered to determine which task is accessing the failure address and kill that task in the end. We used self-developed dax device (which is 2M aligned mapping) , to perform error injection to random address. It turned out that error injected to non-2M-aligned address was causing endless MCE until panic. Because page_mapped_in_vma() kept resulting wrong address and the task accessing the failure address was never killed properly: [ 3783.719419] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3784.049006] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3784.049190] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3784.448042] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3784.448186] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3784.792026] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3784.792179] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3785.162502] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3785.162633] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3785.461116] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3785.461247] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3785.764730] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3785.764859] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3786.042128] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3786.042259] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3786.464293] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3786.464423] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3786.818090] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3786.818217] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3787.085297] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3787.085424] Memory failure: 0x200c9742: recovery action for dax page: Recovered It took us several weeks to pinpoint this problem, but we eventually used bpftrace to trace the page fault and mce address and successfully identified the issue. Joao added: ; Likely we never reproduce in production because we always pin : device-dax regions in the region align they provide (Qemu does : similarly with prealloc in hugetlb/file backed memory). I think this : bug requires that we touch *unpinned* device-dax regions unaligned to : the device-dax selected alignment (page size i.e. 4K/2M/1G)
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
SUSE Affected 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Affected | — |
Debian Fixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Fixed | 6.11.4-1 |
| sid | Fixed | 6.11.4-1 |
| forky | Fixed | 6.11.4-1 |
| bullseye | Fixed | 0 |
| bookworm | Fixed | 6.1.115-1 |
Red Hat Fixed 1 release
| Version | Status | Fixed in |
|---|---|---|
| 9 | Fixed | — |
References
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.