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[PATCH] hw/i386: Improve bounds checking in OVMF table parsing
From: |
Dov Murik |
Subject: |
[PATCH] hw/i386: Improve bounds checking in OVMF table parsing |
Date: |
Mon, 14 Feb 2022 12:08:57 +0000 |
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(-)
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;
}
base-commit: 48033ad678ae2def43bf0d543a2c4c3d2a93feaf
--
2.25.1
- [PATCH] hw/i386: Improve bounds checking in OVMF table parsing,
Dov Murik <=