In the Linux kernel, the following vulnerability has been resolved: lib/scatterlist: fix length calculations in extract_kvec_to_sg Patch series "Fix bugs in extract_iter_to_sg()", v3. Fix bugs in the kvec and user variants of extract_iter_to_sg. This series is growing due to useful remarks made by sashiko.dev. The main bugs are: - The length for an sglist entry when extracting from a kvec can exceed the number of bytes in the page. This is obviously not intended. - When extracting a user buffer the sglist is temporarily used as a scratch buffer for extracted page pointers. If the sglist already contains some elements this scratch buffer could overlap with existing entries in the sglist. The series adds test cases to the kunit_iov_iter test that demonstrate all of these bugs. Additionally, there is a memory leak fix for the test itself. The bugs were orignally introduced into kernel v6.3 where the function lived in fs/netfs/iterator.c. It was later moved to lib/scatterlist.c in v6.5. Thus the actual fix is only marked for backports to v6.5+. This patch (of 5): When extracting from a kvec to a scatterlist, do not cross page boundaries. The required length was already calculated but not used as intended. Adjust the copied length if the loop runs out of sglist entries without extracting everything. While there, return immediately from extract_iter_to_sg if there are no sglist entries at all. A subsequent commit will add kunit test cases that demonstrate that the patch is necessary.
When extracting data from kvec to scatterlist, the entry length can exceed the number of bytes available on a memory page, which violates data structure integrity. Additionally, when extracting a user buffer, scatterlist is temporarily used as a helper buffer for page pointers — if scatterlist already contains some elements, the helper buffer can overlap them, leading to existing data corruption. The errors were originally introduced in kernel v6.3 (file fs/netfs/iterator.c) and later moved to lib/scatterlist.c in v6.5.
An attacker can cause kernel memory corruption, potentially resulting in breach of confidentiality, integrity and system availability, including the possibility of privilege escalation or system destabilization.
Patches available from the vendor should be applied according to references (commits available in kernel.org repository: 07b7d66e65d9, 3f17500e86d7, 8fbba6829057, 9d38756d0a93, e5e22fc99634). It is recommended to update to a kernel version containing the indicated fixes.
Linux kernel version 6.5 and later (function in lib/scatterlist.c); patches intended for backporting to v6.5+ branches
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HLinux Kernel
OSLinux6.3 – 6.6.140 (excl.)6.7 – 6.12.88 (excl.)6.13 – 6.18.30 (excl.)6.19 – 7.0.7 (excl.)
Related vulnerabilities
Type confusion w V8 (Google Chrome) — zdalne uszkodzenie sterty
Commvault Command Center – nieuwierzytelniony RCE przez path traversal w ZIP
RCE przez YAML deserialization w IBM Aspera Faspex
RCE w VMware Workspace ONE Access i Identity Manager poprzez server-side template injection
Command Injection w VMware Workspace One Access i Identity Manager