qga/commands-posix: fix use after free of local_err

local_err is used several times in guest_suspend(). Setting non-NULL
local_err will crash, so let's zero it after freeing. Also fix possible
leak of local_err in final if().

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20200324153630.11882-7-vsementsov@virtuozzo.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index 93474ff7701e2e176e0dc38290f8f91df9233ce1..cc69b82704ec974f172f70763568dfdef05a0ca8 100644 (file)
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -1773,6 +1773,7 @@ static void guest_suspend(SuspendMode mode, Error **errp)
     }
 
     error_free(local_err);
+    local_err = NULL;
 
     if (pmutils_supports_mode(mode, &local_err)) {
         mode_supported = true;
@@ -1784,6 +1785,7 @@ static void guest_suspend(SuspendMode mode, Error **errp)
     }
 
     error_free(local_err);
+    local_err = NULL;
 
     if (linux_sys_state_supports_mode(mode, &local_err)) {
         mode_supported = true;
@@ -1791,6 +1793,7 @@ static void guest_suspend(SuspendMode mode, Error **errp)
     }
 
     if (!mode_supported) {
+        error_free(local_err);
         error_setg(errp,
                    "the requested suspend mode is not supported by the guest");
     } else {