Bug 2164424 (CVE-2022-4696) - CVE-2022-4696 kernel: user-after-free during IORING_OP_SPLICE operation
Summary: CVE-2022-4696 kernel: user-after-free during IORING_OP_SPLICE operation
Alias: CVE-2022-4696
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 2164425
Blocks: 2160255
TreeView+ depends on / blocked
Reported: 2023-01-25 14:13 UTC by Mauro Matteo Cascella
Modified: 2023-01-27 23:52 UTC (History)
37 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
A use-after-free flaw was found in the io_uring subsystem of the Linux kernel. This issue occurs during the IORING_OP_SPLICE operation due to a missing IO_WQ_WORK_FILES flag, leading to an invalid decrease of its reference counter and later causing the use-after-free vulnerability. This flaw allows a local user to crash or potentially escalate their privileges on the system.
Clone Of:
Last Closed: 2023-01-27 23:52:13 UTC

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Description Mauro Matteo Cascella 2023-01-25 14:13:04 UTC
A use-after-free vulnerability was found in the Linux kernel through io_uring and the IORING_OP_SPLICE operation. IORING_OP_SPLICE is missing the IO_WQ_WORK_FILES flag, which signals that the operation won't use current->nsproxy, so its reference counter is not increased. This assumption is not always true as calling io_splice on specific files will call the get_uts function which will use current->nsproxy leading to invalidly decreasing its reference counter later causing the use-after-free vulnerability.

Upstream commit:

Comment 1 Mauro Matteo Cascella 2023-01-25 14:13:33 UTC
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 2164425]

Comment 3 Justin M. Forbes 2023-01-25 14:40:09 UTC
This was fixed for Fedora with the 5.12 rebases.

Comment 4 Product Security DevOps Team 2023-01-27 23:52:09 UTC
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):


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