fs: fat: fix set_cluster()

Avoid CoverityScan warning SIGN_EXTENSION by changing the type of
parameter size of set_cluster().

Avoid leaking stack content when writing an incomplete last sector.

Reported-by: Coverity (CID: 184096)
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index 1ec72d156b02c04b250a97927219674342abaa2f..9fcf3bcb48eb1fda2f3d999a9e5115a697566649 100644 (file)
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -387,16 +387,22 @@ static __u32 determine_fatent(fsdata *mydata, __u32 entry)
        return next_entry;
 }
 
-/*
- * Write at most 'size' bytes from 'buffer' into the specified cluster.
- * Return 0 on success, -1 otherwise.
+/**
+ * set_cluster() - write data to cluster
+ *
+ * Write 'size' bytes from 'buffer' into the specified cluster.
+ *
+ * @mydata:    data to be written
+ * @clustnum:  cluster to be written to
+ * @buffer:    data to be written
+ * @size:      bytes to be written (but not more than the size of a cluster)
+ * Return:     0 on success, -1 otherwise
  */
 static int
-set_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer,
-            unsigned long size)
+set_cluster(fsdata *mydata, u32 clustnum, u8 *buffer, u32 size)
 {
-       __u32 idx = 0;
-       __u32 startsect;
+       u32 idx = 0;
+       u32 startsect;
        int ret;
 
        if (clustnum > 0)
@@ -438,7 +444,8 @@ set_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer,
 
        if (size) {
                ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
-
+               /* Do not leak content of stack */
+               memset(tmpbuf, 0, mydata->sect_size);
                memcpy(tmpbuf, buffer, size);
                ret = disk_write(startsect, 1, tmpbuf);
                if (ret != 1) {
@@ -872,7 +879,7 @@ set_clusters:
 
                /* set remaining bytes */
                actsize = filesize;
-               if (set_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
+               if (set_cluster(mydata, curclust, buffer, (u32)actsize) != 0) {
                        debug("error: writing cluster\n");
                        return -1;
                }
@@ -889,7 +896,7 @@ set_clusters:
 
                return 0;
 getit:
-               if (set_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
+               if (set_cluster(mydata, curclust, buffer, (u32)actsize) != 0) {
                        debug("error: writing cluster\n");
                        return -1;
                }