On 29/02/2024 15.39, Zhao Liu wrote:
From: Zhao Liu <zhao1....@intel.com>

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 <pbonz...@redhat.com>
Cc: Marcelo Tosatti <mtosa...@redhat.com>
Signed-off-by: Zhao Liu <zhao1....@intel.com>
---
  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 <th...@redhat.com>


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