Address some security concerns in the cgpt tool.

1. Check for potential integer overflow in sector_bytes * sector_count.
2. Added O_NOFOLLOW to open() call - Is this enough?
3. Passing buffer length to GuidToStr(), PMBRToStr().
4. Use unsigned int in GetEntry() to determine stride.
5. Address conversion between UTF16 and UTF8.

Note: The UTF conversion is complex and troublesome, and needs careful
consideration to get right. For now, I've just forced the interpretation of
the partition name to 7-bit ASCII. That's sufficient for the needs of Chrome
OS, and I can file a new issue to handle UTF correctly.

BUG=chrome-os-partner:705
TEST=manual

Running "make runtests" invokes the tests/run_cgpt_tests.sh script, which checks the behavior and output of the cgpt tool.

Review URL: http://codereview.chromium.org/3594010

Change-Id: I5fd29796d8c929527e0cfbc6d5ccbcdc77502c6b

1 files changed, 8 insertions, 8 deletions

diff --git a/cgpt/cmd_boot.c b/cgpt/cmd_boot.c
index 784684a2..56ab1d58 100644
--- a/cgpt/cmd_boot.c
+++ b/cgpt/cmd_boot.c
@@ -34,12 +34,12 @@ static void Usage(void)
 
 int cmd_boot(int argc, char *argv[]) {
   struct drive drive;
-  int partition = 0;
+  uint32_t partition = 0;
   char *bootfile = 0;
   int create_pmbr = 0;
   int retval = 1;
   int gpt_retval;
-  
+
   int c;
   int errorcnt = 0;
   char *e = 0;
@@ -63,7 +63,7 @@ int cmd_boot(int argc, char *argv[]) {
     case 'p':
       create_pmbr = 1;
       break;
-      
+
     case 'h':
       Usage();
       return CGPT_OK;
@@ -98,7 +98,7 @@ int cmd_boot(int argc, char *argv[]) {
     Error("Unable to read PMBR\n");
     goto done;
   }
-    
+
   if (create_pmbr) {
     drive.pmbr.magic[0] = 0x1d;
     drive.pmbr.magic[1] = 0x9a;
@@ -131,7 +131,7 @@ int cmd_boot(int argc, char *argv[]) {
       goto done;
     }
 
-    int index = partition - 1;
+    uint32_t index = partition - 1;
     GptEntry *entry = GetEntry(&drive.gpt, PRIMARY, index);
     memcpy(&drive.pmbr.boot_guid, &entry->unique, sizeof(Guid));
   }
@@ -152,9 +152,9 @@ int cmd_boot(int argc, char *argv[]) {
 
     close(fd);
   }
-      
-  char buf[256];
-  GuidToStr(&drive.pmbr.boot_guid, buf);
+
+  char buf[GUID_STRLEN];
+  GuidToStr(&drive.pmbr.boot_guid, buf, sizeof(buf));
   printf("%s\n", buf);
 
   // Write it all out