Re: [PATCH v4] liveupdate: fix return value on session allocation failure

Mike Rapoport
2026-04-16T14:21:19Z

On Wed, Apr 15, 2026 at 07:37:38PM +0000, Pasha Tatashin wrote:
> When session allocation fails during deserialization, the global 'err'
> variable was not updated before returning. This caused subsequent calls
> to luo_session_deserialize() to incorrectly report success.
>
> Ensure 'err' is set to the error code from PTR_ERR(session). This
> ensures that an error is correctly returned to userspace when it
> attempts to open /dev/liveupdate in the new kernel if deserialization
> failed.
>
> Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
> Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>

Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

> ---
> kernel/liveupdate/luo_session.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/kernel/liveupdate/luo_session.c b/kernel/liveupdate/luo_session.c
> index a3327a28fc1f..7a42385dabe2 100644
> --- a/kernel/liveupdate/luo_session.c
> +++ b/kernel/liveupdate/luo_session.c
> @@ -514,11 +514,12 @@ int luo_session_deserialize(void)
> {
> struct luo_session_header *sh = &luo_session_global.incoming;
> static bool is_deserialized;
> - static int err;
> + static int saved_err;
> + int err;
>
> /* If has been deserialized, always return the same error code */
> if (is_deserialized)
> - return err;
> + return saved_err;
>
> is_deserialized = true;
> if (!sh->active)
> @@ -547,7 +548,8 @@ int luo_session_deserialize(void)
> pr_warn("Failed to allocate session [%.*s] during deserialization %pe\n",
> (int)sizeof(sh->ser[i].name),
> sh->ser[i].name, session);
> - return PTR_ERR(session);
> + err = PTR_ERR(session);
> + goto save_err;
> }
>
> err = luo_session_insert(sh, session);
> @@ -555,7 +557,7 @@ int luo_session_deserialize(void)
> pr_warn("Failed to insert session [%s] %pe\n",
> session->name, ERR_PTR(err));
> luo_session_free(session);
> - return err;
> + goto save_err;
> }
>
> scoped_guard(mutex, &session->mutex) {
> @@ -565,7 +567,7 @@ int luo_session_deserialize(void)
> if (err) {
> pr_warn("Failed to deserialize files for session [%s] %pe\n",
> session->name, ERR_PTR(err));
> - return err;
> + goto save_err;
> }
> }
>
> @@ -574,6 +576,9 @@ int luo_session_deserialize(void)
> sh->ser = NULL;
>
> return 0;
> +save_err:
> + saved_err = err;
> + return err;
> }
>
> int luo_session_serialize(void)
> --
> 2.43.0
>

--
Sincerely yours,
Mike.