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.

A flaw was found in the `xen/gntdev` component of the Linux kernel. When the `gntdev_ioctl_map_grant_ref()` function fails to copy operation results back to userspace, it does not properly release a memory reference. This oversight can lead to a memory leak and a corrupted list entry. A local attacker could exploit this to cause a denial of service by exhausting system memory.

Red Hat Enterprise Linux 10 Not affected kernel Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 8 Not affected kernel Red Hat Enterprise Linux 8 Not affected kernel-rt Red Hat Enterprise Linux 9 Not affected kernel Red Hat Enterprise Linux 9 Not affected kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-72138 https://nvd.nist.gov/vuln/detail/CVE-2026-72138 https://lore.kernel.org/linux-cve-announce/2026081531-CVE-2026-72138-5d33@gregkh/T