[16/17] target/i386/sev: Fix missing ERRP_GUARD() for error_prepend()

Commit Message

Zhao Liu Feb. 29, 2024, 2:39 p.m. UTC

From: Zhao Liu <[e-mail]>

As the comment in qapi/error, passing @errp to error_prepend() requires
ERRP_GUARD():

* = Why, when and how to use ERRP_GUARD() =
*
* Without ERRP_GUARD(), use of the @errp parameter is restricted:
...
* - It should not be passed to error_prepend(), error_vprepend() or
*   error_append_hint(), because that doesn't work with &error_fatal.
* ERRP_GUARD() lifts these restrictions.
*
* To use ERRP_GUARD(), add it right at the beginning of the function.
* @errp can then be used without worrying about the argument being
* NULL or &error_fatal.

ERRP_GUARD() could avoid the case when @errp is the pointer of
error_fatal, the user can't see this additional information, because
exit() happens in error_setg earlier than information is added [1].

The sev_inject_launch_secret() passes @errp to error_prepend(), and as
an APIs defined in target/i386/sev.h, it is necessary to protect its
@errp with ERRP_GUARD().

To avoid the issue like [1] said, add missing ERRP_GUARD() at the
beginning of this function.

[1]: Issue description in the commit message of commit ae7c80a7bd73
     ("error: New macro ERRP_GUARD()").

Cc: Paolo Bonzini <[e-mail]>
Cc: Marcelo Tosatti <[e-mail]>
Signed-off-by: Zhao Liu <[e-mail]>
---
 target/i386/sev.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Thomas Huth Feb. 29, 2024, 5:36 p.m. UTC | #1

On 29/02/2024 15.39, Zhao Liu wrote:
> From: Zhao Liu <[e-mail]>
> 
> As the comment in qapi/error, passing @errp to error_prepend() requires
> ERRP_GUARD():
> 
> * = Why, when and how to use ERRP_GUARD() =
> *
> * Without ERRP_GUARD(), use of the @errp parameter is restricted:
> ...
> * - It should not be passed to error_prepend(), error_vprepend() or
> *   error_append_hint(), because that doesn't work with &error_fatal.
> * ERRP_GUARD() lifts these restrictions.
> *
> * To use ERRP_GUARD(), add it right at the beginning of the function.
> * @errp can then be used without worrying about the argument being
> * NULL or &error_fatal.
> 
> ERRP_GUARD() could avoid the case when @errp is the pointer of
> error_fatal, the user can't see this additional information, because
> exit() happens in error_setg earlier than information is added [1].
> 
> The sev_inject_launch_secret() passes @errp to error_prepend(), and as
> an APIs defined in target/i386/sev.h, it is necessary to protect its
> @errp with ERRP_GUARD().
> 
> To avoid the issue like [1] said, add missing ERRP_GUARD() at the
> beginning of this function.
> 
> [1]: Issue description in the commit message of commit ae7c80a7bd73
>       ("error: New macro ERRP_GUARD()").
> 
> Cc: Paolo Bonzini <[e-mail]>
> Cc: Marcelo Tosatti <[e-mail]>
> Signed-off-by: Zhao Liu <[e-mail]>
> ---
>   target/i386/sev.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/target/i386/sev.c b/target/i386/sev.c
> index 173de91afe7d..72930ff0dcc5 100644
> --- a/target/i386/sev.c
> +++ b/target/i386/sev.c
> @@ -1044,6 +1044,7 @@ sev_encrypt_flash(uint8_t *ptr, uint64_t len, Error **errp)
>   int sev_inject_launch_secret(const char *packet_hdr, const char *secret,
>                                uint64_t gpa, Error **errp)
>   {
> +    ERRP_GUARD();
>       struct kvm_sev_launch_secret input;
>       g_autofree guchar *data = NULL, *hdr = NULL;
>       int error, ret = 1;

Reviewed-by: Thomas Huth <[e-mail]>

Patch

diff --git a/target/i386/sev.c b/target/i386/sev.c
index 173de91afe7d..72930ff0dcc5 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -1044,6 +1044,7 @@  sev_encrypt_flash(uint8_t *ptr, uint64_t len, Error **errp)
 int sev_inject_launch_secret(const char *packet_hdr, const char *secret,
                              uint64_t gpa, Error **errp)
 {
+    ERRP_GUARD();
     struct kvm_sev_launch_secret input;
     g_autofree guchar *data = NULL, *hdr = NULL;
     int error, ret = 1;