CVE-2022-48801 in Linux
Summary
by MITRE • 07/16/2024
In the Linux kernel, the following vulnerability has been resolved:
iio: buffer: Fix file related error handling in IIO_BUFFER_GET_FD_IOCTL
If we fail to copy the just created file descriptor to userland, we try to clean up by putting back 'fd' and freeing 'ib'. The code uses put_unused_fd() for the former which is wrong, as the file descriptor was already published by fd_install() which gets called internally by anon_inode_getfd().
This makes the error handling code leaving a half cleaned up file descriptor table around and a partially destructed 'file' object, allowing userland to play use-after-free tricks on us, by abusing the still usable fd and making the code operate on a dangling 'file->private_data' pointer.
Instead of leaving the kernel in a partially corrupted state, don't attempt to explicitly clean up and leave this to the process exit path that'll release any still valid fds, including the one created by the previous call to anon_inode_getfd(). Simply return -EFAULT to indicate the error.
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Analysis
by VulDB Data Team • 09/25/2025
The vulnerability described in CVE-2022-48801 resides within the Linux kernel's Industrial I/O (IIO) subsystem, specifically in the buffer handling mechanism. This issue affects the IIO_BUFFER_GET_FD_IOCTL operation which is used to retrieve file descriptors associated with IIO buffer operations. The problem manifests when the kernel attempts to handle errors during the process of copying a newly created file descriptor to user space, creating a dangerous state where cleanup operations become problematic and potentially exploitable.
The technical flaw stems from improper error handling within the IIO buffer subsystem's file descriptor management. When the kernel fails to copy the created file descriptor to user space, it attempts to perform cleanup by calling put_unused_fd() on the file descriptor that was already published through fd_install() which is invoked internally by anon_inode_getfd(). This sequence creates a race condition and inconsistent state where a file descriptor remains in the file descriptor table but is in a partially cleaned up state. The kernel's file descriptor table contains a reference to a file object that has been partially destroyed, leaving behind a dangling pointer that can be exploited by malicious userland processes.
This vulnerability creates a use-after-free condition that allows attackers to manipulate the kernel's internal state through the still functional file descriptor. The partially destructed file object maintains a valid file descriptor entry in the process's file descriptor table, but its private_data pointer points to freed memory. This enables attackers to perform operations that could lead to privilege escalation, information disclosure, or system instability. The vulnerability specifically targets the cleanup path of the IIO buffer subsystem where error handling logic fails to properly account for the state transitions that occur during file descriptor creation and publication.
The operational impact of this vulnerability extends beyond simple memory corruption as it provides potential for privilege escalation within the kernel context. Attackers can leverage the half-cleanup state to manipulate kernel data structures through the dangling private_data pointer, potentially executing arbitrary code with kernel privileges. The vulnerability affects systems running Linux kernels that include the IIO subsystem and are configured to handle buffer operations through the specific IOCTL interface mentioned in the CVE. This issue demonstrates the critical importance of proper error handling in kernel space, particularly when dealing with resource management and file descriptor operations.
Security mitigations for this vulnerability involve applying the kernel patch that corrects the error handling logic by simply returning -EFAULT instead of attempting manual cleanup operations. This approach ensures that the kernel's normal cleanup mechanisms, particularly those triggered during process exit, handle the resource deallocation properly without leaving inconsistent states. The fix aligns with established kernel security practices that emphasize minimal error handling in critical paths and rely on established cleanup mechanisms rather than custom recovery logic. This vulnerability also relates to CWE-415 which addresses double free errors and CWE-416 which covers use after free conditions, both of which are fundamental concerns in kernel security. The ATT&CK framework would categorize this as a privilege escalation technique through kernel memory corruption, potentially falling under the T1068 technique for exploiting vulnerabilities in kernel space.