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gen_init_cpio: Avoid race between call to stat() and call to open()

In usr/gen_init_cpio.c::cpio_mkfile() a call to stat() is made based on
pathname, subsequently the file is open()'ed and then the value of the
initial stat() call is used to allocate a buffer. This is not safe since
the file may change between the call to stat() and the call to open().
Safer to just open() the file and then do fstat() using the filedescriptor
returned by open.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Acked-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
Jesper Juhl преди 14 години
родител
ревизия
96aebafa63
променени са 1 файла, в които са добавени 6 реда и са изтрити 6 реда
  1. 6 6
      usr/gen_init_cpio.c

+ 6 - 6
usr/gen_init_cpio.c

@@ -309,18 +309,18 @@ static int cpio_mkfile(const char *name, const char *location,
 
 	mode |= S_IFREG;
 
-	retval = stat (location, &buf);
-	if (retval) {
-		fprintf (stderr, "File %s could not be located\n", location);
-		goto error;
-	}
-
 	file = open (location, O_RDONLY);
 	if (file < 0) {
 		fprintf (stderr, "File %s could not be opened for reading\n", location);
 		goto error;
 	}
 
+	retval = fstat (file, &buf);
+	if (retval) {
+		fprintf (stderr, "File %s could not be stat()'ed\n", location);
+		goto error;
+	}
+
 	filebuf = malloc(buf.st_size);
 	if (!filebuf) {
 		fprintf (stderr, "out of memory\n");