[PATCH] lib: fwts_multiproc: add sanity check to data->size to clean up static analysis warning

[Colin King]

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

Static analysis warns that the data->size is not validated so add a simple
sanity check on the size.  This is a moot point as we know the size is never
going to be huge and we have to trust the given table size, but this at least
sanity checks things and keeps static analyzers happy.

Addresses-Coverity: ("Untrusted value as argument")
Signed-off-by: Colin Ian King <colin.king at canonical.com>
---
 src/lib/src/fwts_multiproc.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/lib/src/fwts_multiproc.c b/src/lib/src/fwts_multiproc.c
index 1402c1a7..c79c0be3 100644
--- a/src/lib/src/fwts_multiproc.c
+++ b/src/lib/src/fwts_multiproc.c
@@ -39,6 +39,8 @@
 #define BIOS_START      (0x000e0000)            /* Start of BIOS memory */
 #define BIOS_END        (0x000fffff)            /* End of BIOS memory */
 
+#define MAX_SIZE(x)	(1UL << (sizeof(x) * 8))
+
 /*
  *  fwts_mp_get_address()
  *	scan for _MP_ floating pointer, set phys_addr if found.
@@ -111,6 +113,7 @@ int fwts_mp_data_get(fwts_mp_data *data)
 	void *mem;
 	uint8_t *tmp;
 	fwts_mp_config_table_header *header;
+	int max_data_size;
 
 	if (data == NULL)
 		return FWTS_ERROR;
@@ -130,6 +133,10 @@ int fwts_mp_data_get(fwts_mp_data *data)
 
 	data->size = header->base_table_length +
 		((header->spec_rev == 1) ? 0 : header->extended_table_length);
+	max_data_size = MAX_SIZE(header->base_table_length) +
+			MAX_SIZE(header->extended_table_length);
+	if (data->size < 0 || data->size > max_data_size)
+		return FWTS_ERROR;
 
 	/* Remap with full header and table now we know how big it is */
 	(void)fwts_munmap(mem, sizeof(fwts_mp_config_table_header));
-- 
2.24.0