diff mbox series

hw/i386: Improve bounds checking in OVMF table parsing

Message ID 20220214120857.1147288-1-dovmurik@linux.ibm.com
State New
Headers show
Series hw/i386: Improve bounds checking in OVMF table parsing | expand

Commit Message

Dov Murik Feb. 14, 2022, 12:08 p.m. UTC 
When pc_system_parse_ovmf_flash() parses the optional GUIDed table in
the end of the OVMF flash memory area, the table length field is checked
for sizes that are too small, but doesn't error on sizes that are too
big (bigger than the flash content itself).

Add a check for maximal size of the OVMF table, and add an error report
in case the size is invalid.

Signed-off-by: Dov Murik <dovmurik@linux.ibm.com>
---
 hw/i386/pc_sysfw_ovmf.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)


base-commit: 48033ad678ae2def43bf0d543a2c4c3d2a93feaf
diff mbox series

Patch

diff --git a/hw/i386/pc_sysfw_ovmf.c b/hw/i386/pc_sysfw_ovmf.c
index f4dd92c588..0663f3f54a 100644
--- a/hw/i386/pc_sysfw_ovmf.c
+++ b/hw/i386/pc_sysfw_ovmf.c
@@ -24,6 +24,7 @@ 
  */
 
 #include "qemu/osdep.h"
+#include "qemu/error-report.h"
 #include "hw/i386/pc.h"
 #include "cpu.h"
 
@@ -66,7 +67,13 @@  void pc_system_parse_ovmf_flash(uint8_t *flash_ptr, size_t flash_size)
     ptr -= sizeof(uint16_t);
     tot_len = le16_to_cpu(*(uint16_t *)ptr) - sizeof(guid) - sizeof(uint16_t);
 
-    if (tot_len <= 0) {
+    if (tot_len < 0 || tot_len > flash_size - 50) {
+        error_report("OVMF table has invalid size %d", tot_len);
+        return;
+    }
+
+    if (tot_len == 0) {
+        /* no entries in the OVMF table */
         return;
     }