CVE-2024-50250
fsdax: dax_unshare_iter needs to copy entire blocks
Severity Score
Exploit Likelihood
Affected Versions
Public Exploits
0Exploited in Wild
-Decision
Descriptions
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.
CVSS Scores
SSVC
- Decision:-
Timeline
- 2024-10-21 CVE Reserved
- 2024-11-09 CVE Published
- 2024-11-09 CVE Updated
- 2024-11-10 EPSS Updated
- ---------- Exploited in Wild
- ---------- KEV Due Date
- ---------- First Exploit
CWE
CAPEC
References (6)
URL | Tag | Source |
---|---|---|
https://git.kernel.org/stable/c/1bec6782a25c9b92c203ea7a1b3e3dc6a468cbc4 | Vuln. Introduced | |
https://git.kernel.org/stable/c/d984648e428bf88cbd94ebe346c73632cb92fffb | Vuln. Introduced |
URL | Date | SRC |
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URL | Date | SRC |
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Affected Vendors, Products, and Versions
Vendor | Product | Version | Other | Status | ||||||
---|---|---|---|---|---|---|---|---|---|---|
Vendor | Product | Version | Other | Status | <-- --> | Vendor | Product | Version | Other | Status |
Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 6.1.113 < 6.1.116 Search vendor "Linux" for product "Linux Kernel" and version " >= 6.1.113 < 6.1.116" | en |
Affected
| ||||||
Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 6.2 < 6.6.60 Search vendor "Linux" for product "Linux Kernel" and version " >= 6.2 < 6.6.60" | en |
Affected
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Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 6.2 < 6.11.7 Search vendor "Linux" for product "Linux Kernel" and version " >= 6.2 < 6.11.7" | en |
Affected
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Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 6.2 < 6.12-rc6 Search vendor "Linux" for product "Linux Kernel" and version " >= 6.2 < 6.12-rc6" | en |
Affected
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