[PULL v2 13/16] acpi: use constants as strncpy limit

[Michael S. Tsirkin]

gcc is not smart enough to figure out length was validated before use as
strncpy limit, resulting in this warning:

inlined from ‘virt_set_oem_table_id’ at ../../hw/arm/virt.c:2197:5:
/usr/include/aarch64-linux-gnu/bits/string_fortified.h:106:10: error:
‘__builtin_strncpy’ specified bound depends on the length of the
source argument [-Werror=stringop-overflow=]

Simplify things by using a constant limit instead.

Fixes: 97fc5d507fca ("acpi: Permit OEM ID and OEM table ID fields to be 
changed")
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/arm/virt.c     | 4 ++--
 hw/i386/microvm.c | 4 ++--
 hw/i386/pc.c      | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 0c65fe38a0..371147f3ae 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -2173,7 +2173,7 @@ static void virt_set_oem_id(Object *obj, const char 
*value, Error **errp)
         return;
     }
 
-    strncpy(vms->oem_id, value, len + 1);
+    strncpy(vms->oem_id, value, 6);
 }
 
 static char *virt_get_oem_table_id(Object *obj, Error **errp)
@@ -2194,7 +2194,7 @@ static void virt_set_oem_table_id(Object *obj, const char 
*value,
                    "User specified oem-table-id value is bigger than 8 bytes 
in size");
         return;
     }
-    strncpy(vms->oem_table_id, value, len + 1);
+    strncpy(vms->oem_table_id, value, 8);
 }
 
 
diff --git a/hw/i386/microvm.c b/hw/i386/microvm.c
index 1dc2956e72..4e0cf4c522 100644
--- a/hw/i386/microvm.c
+++ b/hw/i386/microvm.c
@@ -668,7 +668,7 @@ static void microvm_machine_set_oem_id(Object *obj, const 
char *value,
         return;
     }
 
-    strncpy(mms->oem_id, value, len + 1);
+    strncpy(mms->oem_id, value, 6);
 }
 
 static char *microvm_machine_get_oem_table_id(Object *obj, Error **errp)
@@ -690,7 +690,7 @@ static void microvm_machine_set_oem_table_id(Object *obj, 
const char *value,
           "8 bytes in size");
         return;
     }
-    strncpy(mms->oem_table_id, value, len + 1);
+    strncpy(mms->oem_table_id, value, 8);
 }
 
 static void microvm_machine_initfn(Object *obj)
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 437977c49e..8aa85dec54 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1630,7 +1630,7 @@ static void pc_machine_set_oem_id(Object *obj, const char 
*value, Error **errp)
         return;
     }
 
-    strncpy(pcms->oem_id, value, len + 1);
+    strncpy(pcms->oem_id, value, 6);
 }
 
 static char *pc_machine_get_oem_table_id(Object *obj, Error **errp)
@@ -1652,7 +1652,7 @@ static void pc_machine_set_oem_table_id(Object *obj, 
const char *value,
           "8 bytes in size");
         return;
     }
-    strncpy(pcms->oem_table_id, value, len + 1);
+    strncpy(pcms->oem_table_id, value, 8);
 }
 
 static void pc_machine_initfn(Object *obj)
-- 
MST