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a7c1290eef
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.
Cc: stable@vger.kernel.org
Fixes: 7063fbf226 ("[PATCH] configfs: User-driven configuration filesystem")
Signed-off-by: Vasileios Almpanis <vasilisalmpanis@gmail.com>
Tested-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20260730093435.195441-2-vasilisalmpanis@gmail.com
Signed-off-by: Breno Leitao <leitao@debian.org>
278 lines
7.1 KiB
278 lines
7.1 KiB