Re: [PATCH for-4.22] tools/libfsimage: Remove the XEN_FSIMAGE_FSDIR environment variable

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

On 7/2/26 5:03 PM, Andrew Cooper wrote:
> This was reported to the security team, demonstrating that code execution
> could be achieved, but without a demonstration of a priviliege boundary being
> bypassed.
>
> Still, it's a high risk path with no obvious evidence of having been used even
> for debugging, so remove the environment variable and use the build time
> $(libdir)/xenfsimage path only.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> CC: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> CC: Michal Orzel <michal.orzel@xxxxxxx>
> CC: Jan Beulich <jbeulich@xxxxxxxx>
> CC: Julien Grall <julien@xxxxxxx>
> CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> CC: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
>
> For 4.22.  This was supposed to be posted earlier but fell through the cracks.
> Given it's borderline-security aspect, we don't want to delay it any further.
> ---
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>

>   CHANGELOG.md                             | 1 +
>   tools/libfsimage/common/fsimage_plugin.c | 5 +----
>   2 files changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/CHANGELOG.md b/CHANGELOG.md
> index ef4e6ae9c459..0a4e5f013cb1 100644
> --- a/CHANGELOG.md
> +++ b/CHANGELOG.md
> @@ -63,6 +63,7 @@ The format is based on [Keep a 
> Changelog](https://keepachangelog.com/en/1.0.0/)
>   
>    - Removed xenpm tool on non-x86 platforms as it doesn't actually provide
>      anything useful outside of x86.
> + - Removed the XEN_FSIMAGE_FSDIR environment variable.
>   
>   ## [4.21.0](https://xenbits.xenproject.org/gitweb/?p=xen.git;a=shortlog;h=RELEASE-4.21.0) - 2025-11-19
>   
Acked-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>


> diff --git a/tools/libfsimage/common/fsimage_plugin.c 
> b/tools/libfsimage/common/fsimage_plugin.c
> index d0cb9e96a654..539dc247356a 100644
> --- a/tools/libfsimage/common/fsimage_plugin.c
> +++ b/tools/libfsimage/common/fsimage_plugin.c
> @@ -121,7 +121,7 @@ static int init_plugin(const char *lib)
>   
>   int fsi_init(void)
>   {
> -       const char *fsdir = getenv("XEN_FSIMAGE_FSDIR");
> +       const char *fsdir = FSIMAGE_FSDIR;
>         struct dirent *dp = NULL;
>         DIR *dir = NULL;
>         char *tmp = NULL;
> @@ -129,9 +129,6 @@ int fsi_init(void)
>         int err;
>         int ret = -1;
>   
> -	if (fsdir == NULL)
> -               fsdir = FSIMAGE_FSDIR;
> -
>         if ((name_max = pathconf(fsdir, _PC_NAME_MAX)) == -1)
>                 goto fail;
>   
>
> base-commit: ad9f564a5d840389cbf1b230086e1dd8257d8820

~ Oleksii