Loop with Unreachable Exit Condition ('Infinite Loop') Affecting kernel-debug-uki-virt package, versions *
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applications- Snyk IDSNYK-RHEL9-KERNELDEBUGUKIVIRT-8380190
- published14 Nov 2024
- disclosed9 Nov 2024
Introduced: 9 Nov 2024
CVE-2024-50250 (opens in a new tab)How to fix?
There is no fixed version for RHEL:9 kernel-debug-uki-virt.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-debug-uki-virt package and not the kernel-debug-uki-virt package as distributed by RHEL.
See How to fix? for RHEL:9 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
fsdax: dax_unshare_iter needs to copy entire blocks
The code that copies data from srcmap to iomap in dax_unshare_iter is very very broken, which bfoster's recent fsx changes have exposed.
If the pos and len passed to dax_file_unshare are not aligned to an fsblock boundary, the iter pos and length in the _iter function will reflect this unalignment.
dax_iomap_direct_access always returns a pointer to the start of the kmapped fsdax page, even if its pos argument is in the middle of that page. This is catastrophic for data integrity when iter->pos is not aligned to a page, because daddr/saddr do not point to the same byte in the file as iter->pos. Hence we corrupt user data by copying it to the wrong place.
If iter->pos + iomap_length() in the _iter function not aligned to a page, then we fail to copy a full block, and only partially populate the destination block. This is catastrophic for data confidentiality because we expose stale pmem contents.
Fix both of these issues by aligning copy_pos/copy_len to a page boundary (remember, this is fsdax so 1 fsblock == 1 base page) so that we always copy full blocks.
We're not done yet -- there's no call to invalidate_inode_pages2_range, so programs that have the file range mmap'd will continue accessing the old memory mapping after the file metadata updates have completed.
Be careful with the return value -- if the unshare succeeds, we still need to return the number of bytes that the iomap iter thinks we're operating on.
References
- https://access.redhat.com/security/cve/CVE-2024-50250
- https://git.kernel.org/stable/c/50793801fc7f6d08def48754fb0f0706b0cfc394
- https://git.kernel.org/stable/c/8e9c0f500b42216ef930f5c0d1703989a451913d
- https://git.kernel.org/stable/c/9bc18bb476e50e32e5d08f2734d63d63e0fa528c
- https://git.kernel.org/stable/c/bdbc96c23197d773a7d1bf03e4f11de593b0ff28