[PATCH 1/5] dmi: dmicheck: ensure mmap'd SMBIOS data is readable before accessing it

[Colin King]

From: Colin Ian King <colin.king at canonical.com>

We need to check we don't get SIGSEGV or SIGBUS errors when reading
the mmap'd SMBIOS data before we try and access it. Use the fwts_safe_memread
check on the data to sanity check these mappings.

Signed-off-by: Colin Ian King <colin.king at canonical.com>
---
 src/dmi/dmicheck/dmicheck.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/dmi/dmicheck/dmicheck.c b/src/dmi/dmicheck/dmicheck.c
index 5f010f53..306a0088 100644
--- a/src/dmi/dmicheck/dmicheck.c
+++ b/src/dmi/dmicheck/dmicheck.c
@@ -332,6 +332,12 @@ static void* dmi_table_smbios(fwts_framework *fw, fwts_smbios_entry *entry)
 
 	mem = fwts_mmap(addr, length);
 	if (mem != FWTS_MAP_FAILED) {
+		/* Can we safely copy the table? */
+		if (fwts_safe_memread((void *)addr, length) != FWTS_OK) {
+			fwts_log_info(fw, "SMBIOS table at %p cannot be read", (void *)addr);
+			(void)fwts_munmap(mem, length);
+			return NULL;
+		}
 		table = malloc(length);
 		if (table)
 			memcpy(table, mem, length);
@@ -373,6 +379,12 @@ static void* dmi_table_smbios30(fwts_framework *fw, fwts_smbios30_entry *entry)
 
 	mem = fwts_mmap(addr, length);
 	if (mem != FWTS_MAP_FAILED) {
+		/* Can we safely copy the table? */
+		if (fwts_safe_memread((void *)addr, length) != FWTS_OK) {
+			fwts_log_info(fw, "SMBIOS table at %p cannot be read", (void *)addr);
+			(void)fwts_munmap(mem, length);
+			return NULL;
+		}
 		table = malloc(length);
 		if (table)
 			fwts_memcpy_unaligned(table, mem, length);
-- 
2.11.0