CVE-2026-72138 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
xen/gntdev: fix error handling in ioctl
When gntdev_ioctl_map_grant_ref() fails to copy the operation result back to userspace after successfully adding the mapping to the list, the error path returns -EFAULT without releasing the reference acquired by gntdev_alloc_map(). The mapping remains in priv->maps with a refcount of 1, causing a memory leak and a dangling list entry.
Additionally, gntdev_add_map() may modify map->index to avoid overlap with existing mappings. Therefore, the index returned to userspace must be obtained after gntdev_add_map() completes.
Fix this by holding the mutex across gntdev_add_map(), retrieving the correct index, and copy_to_user(). If copy_to_user() fails, remove the mapping from the list and release the reference while still holding the lock.
Fix these issues by properly handling all error cases.
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