Bug 2174754 (CVE-2023-23586) - CVE-2023-23586 kernel: io_uring: read use-after-free can lead to kernel memory leak
Summary: CVE-2023-23586 kernel: io_uring: read use-after-free can lead to kernel memor...
Keywords:
Status: CLOSED NOTABUG
Alias: CVE-2023-23586
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks: 2171897
TreeView+ depends on / blocked
 
Reported: 2023-03-02 11:40 UTC by Mauro Matteo Cascella
Modified: 2023-03-02 13:40 UTC (History)
37 users (show)

Fixed In Version: kernel 5.12
Doc Type: If docs needed, set a value
Doc Text:
A use-after-free vulnerability was discovered in the Linux kernel's io_uring subsystem. It was found that it is possible to insert a time namespace's vvar page to process memory space via a page fault. When this time namespace is destroyed, the vvar page is also freed, but not removed from the process' memory, and a next page allocated by the kernel will be still available from the user-space process. This (read-only) use-after-free vulnerability can lead to kernel memory leak.
Clone Of:
Environment:
Last Closed: 2023-03-02 13:40:56 UTC
Embargoed:

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Description Mauro Matteo Cascella 2023-03-02 11:40:01 UTC 
Due to a vulnerability in the io_uring subsystem, it is possible to leak kernel memory information to the user process. timens_install calls current_is_single_threaded to determine if the current process is single-threaded, but this call does not consider io_uring's io_worker threads, thus it is possible to insert a time namespace's vvar page to process's memory space via a page fault. When this time namespace is destroyed, the vvar page is also freed, but not removed from the process' memory, and a next page allocated by the kernel will be still available from the user-space process and can leak memory contents via this (read-only) use-after-free vulnerability. We recommend upgrading past version 5.10.161 or commit:

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/io_uring?h=linux-5.10.y&id=788d0824269bef539fe31a785b1517882eafed93
Comment 1 Mauro Matteo Cascella 2023-03-02 11:43:40 UTC 
According to https://www.linuxkernelcves.com/cves/CVE-2023-23586, this flaw was fixed in upstream kernel 5.12 via https://github.com/torvalds/linux/commit/4379bf8bd70b5de6bba7d53015b0c36c57a634ee.
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