64 bit problem in fs/jffs2/wbuf.c

[Jörn Engel]

Hi!

I've tripped into a strange problem while modifying the jffs2 nand
support for nor flashes with ecc checking.

The problem appears to be that jffs2_flash_writev defines the
parameter "to" to be loff_t, which is 64 bit (at least on ppc). Only
the lower 32 bit appear to be used and the upper should be all zeros.
But I have one occasion, where the high bits contain 0xc02fdd18, which
causes a sanity check in wbuf.c, line 347 to fail.

A straightforward fix appears to be a cast, the patch is appended.
The high bits should not contain any junk in the first place, but at
least, this ignores them in this position.

Thomas or David, is this a really stupid idea or can I search for
further bugs elsewhere?

Joern

--- wbuf.c	Wed Jun 19 18:56:26 2002
+++ wbuf.c.new	Wed Jun 26 11:27:27 2002
@@ -234,7 +234,7 @@
 		c->wbuf_len = PAGE_MOD(to);			
 	} 
 
-	if (to != PAD(c->wbuf_ofs + c->wbuf_len)) {
+	if ((unsigned long)to != PAD(c->wbuf_ofs + c->wbuf_len)) {
 		/* We're not writing immediately after the writebuffer. Bad. */
 		printk(KERN_CRIT "jffs2_flash_writev(): Non-contiguous write to %08lx\n", (unsigned long)to);
 		if (c->wbuf_len)