commit f717a6ed5b25287fa9417096f90e7c047ace0c15
author Jean-Baptiste Queru <jbq@google.com> Tue May 29 08:45:33 2012 -0700
committer android code review <noreply-gerritcodereview@google.com> Tue May 29 08:45:34 2012 -0700
tree 5a6efa49bc9563936d9eb661b427a9769658e24f
parent e1dd6c88cff4f71c298921ef34f7662eb227aacf
parent fe7400ddb5e99a790cd3977f9e5151d8ea929a14

Merge "Fix division-by-zero when reading partition tables"

boot.c

diff --git a/boot.c b/boot.c
index 54d800f..6e797fd 100644
--- a/boot.c
+++ b/boot.c
@@ -193,12 +193,6 @@
 		/* Check backup FSInfo?					XXX */
 	}
 
-	boot->ClusterOffset = (boot->RootDirEnts * 32 + boot->BytesPerSec - 1)
-	    / boot->BytesPerSec
-	    + boot->ResSectors
-	    + boot->FATs * boot->FATsecs
-	    - CLUST_FIRST * boot->SecPerClust;
-
 	if (boot->BytesPerSec % DOSBOOTBLOCKSIZE != 0) {
 		pfatal("Invalid sector size: %u", boot->BytesPerSec);
 		return FSFATAL;
@@ -207,11 +201,22 @@
 		pfatal("Invalid cluster size: %u", boot->SecPerClust);
 		return FSFATAL;
 	}
+	if (boot->BytesPerSec == 0) {
+		pfatal("Invalid sector size: %u", boot->BytesPerSec);
+		return FSFATAL;
+	}
 	if (boot->Sectors) {
 		boot->HugeSectors = 0;
 		boot->NumSectors = boot->Sectors;
 	} else
 		boot->NumSectors = boot->HugeSectors;
+
+	boot->ClusterOffset = (boot->RootDirEnts * 32 + boot->BytesPerSec - 1)
+	    / boot->BytesPerSec
+	    + boot->ResSectors
+	    + boot->FATs * boot->FATsecs
+	    - CLUST_FIRST * boot->SecPerClust;
+
 	boot->NumClusters = (boot->NumSectors - boot->ClusterOffset) / boot->SecPerClust;
 
 	if (boot->flags&FAT32)