CVE-2026-97950configfs: pin the symlink target's dirent instead of chasing ->ci_dentry

Official description

In the Linux kernel, the following vulnerability has been resolved: configfs: pin the symlink target's dirent instead of chasing ->ci_dentry create_link() reads the target's configfs_dirent from item->ci_dentry->d_fsdata, relying on the item reference taken by get_target(). That reference pins the item, not its dentry: the dentry is pinned by DCACHE_PERSISTENT, which configfs_remove_dir() releases via simple_rmdir() while the item is still alive. A symlink racing with rmdir of its target can therefore find ->ci_dentry freed and its dirent released, triggering WARN_ON(!atomic_read(&sd->s_count)) in configfs_get(). Take the dirent in get_target() as well, under ->d_lock and atomically with the item reference, and pass it down to create_link(). A hashed dentry has not been killed yet, so its ->d_fsdata reference keeps the dirent alive there.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/a44744454eafbc158e8c8e3ef8d207076410b195
• https://git.kernel.org/stable/c/846ff40fd57a47e59a41f4e331ec3b34efaddc23
• https://git.kernel.org/stable/c/4f54beb2e7f6d399396466682fba3539bcdcb414
• https://git.kernel.org/stable/c/d47c5de1cd6bfbe1067fc310bf90e4e00205e839
• https://git.kernel.org/stable/c/a7c1290eef60711c10289c056ad32ed1f2b47b12