[PATCH v2] cachefiles: fix dentry leak in cachefiles_open_file()

[Christian Brauner]

On Thu, 29 Aug 2024 16:34:09 +0800, libaokun at huaweicloud.com wrote:
> A dentry leak may be caused when a lookup cookie and a cull are concurrent:
> 
>             P1             |             P2
> -----------------------------------------------------------
> cachefiles_lookup_cookie
>   cachefiles_look_up_object
>     lookup_one_positive_unlocked
>      // get dentry
>                             cachefiles_cull
>                               inode->i_flags |= S_KERNEL_FILE;
>     cachefiles_open_file
>       cachefiles_mark_inode_in_use
>         __cachefiles_mark_inode_in_use
>           can_use = false
>           if (!(inode->i_flags & S_KERNEL_FILE))
>             can_use = true
> 	  return false
>         return false
>         // Returns an error but doesn't put dentry
> 
> [...]

Applied to the vfs.fixes branch of the vfs/vfs.git tree.
Patches in the vfs.fixes branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.fixes

[1/1] cachefiles: fix dentry leak in cachefiles_open_file()
      https://git.kernel.org/vfs/vfs/c/31075a6ed624