x86/pmstat: correct get_cpufreq_para()'s error return value

Commit Message

Jan Beulich March 26, 2025, 11:38 a.m. UTC

copy_to_guest() returns the number of bytes not copied; that's not what
the function should return to its caller though. Convert to returning
-EFAULT instead.

Fixes: 7542c4ff00f2 ("Add user PM control interface")
Reported-by: Andrew Cooper <[e-mail]>
Signed-off-by: Jan Beulich <[e-mail]>

Comments

Andrew Cooper March 26, 2025, 11:40 a.m. UTC | #1

On 26/03/2025 11:38 am, Jan Beulich wrote:
> copy_to_guest() returns the number of bytes not copied; that's not what
> the function should return to its caller though. Convert to returning
> -EFAULT instead.
>
> Fixes: 7542c4ff00f2 ("Add user PM control interface")
> Reported-by: Andrew Cooper <[e-mail]>
> Signed-off-by: Jan Beulich <[e-mail]>

Acked-by: Andrew Cooper <[e-mail]>

Patch

--- a/xen/drivers/acpi/pmstat.c
+++ b/xen/drivers/acpi/pmstat.c
@@ -230,12 +230,12 @@  static int get_cpufreq_para(struct xen_s
 
     for ( i = 0; i < op->u.get_para.freq_num; i++ )
         data[i] = pmpt->perf.states[i].core_frequency * 1000;
-    ret = copy_to_guest(op->u.get_para.scaling_available_frequencies,
-                        data, op->u.get_para.freq_num) ?: ret;
+    ret += copy_to_guest(op->u.get_para.scaling_available_frequencies,
+                         data, op->u.get_para.freq_num);
 
     xfree(data);
     if ( ret )
-        return ret;
+        return -EFAULT;
 
     op->u.get_para.cpuinfo_cur_freq =
         cpufreq_driver.get ? alternative_call(cpufreq_driver.get, op->cpuid)
@@ -272,7 +272,7 @@  static int get_cpufreq_para(struct xen_s
                             gov_num * CPUFREQ_NAME_LEN);
         xfree(scaling_available_governors);
         if ( ret )
-            return ret;
+            return -EFAULT;
 
         op->u.get_para.u.s.scaling_cur_freq = policy->cur;
         op->u.get_para.u.s.scaling_max_freq = policy->max;