[PATCH] mmap.c corner case fix, per David S. Miller

[DervishD <raul@pleyades.net>]

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    Hi Marcelo :)

    This patch fixes the same corner case, but does something useful
even or architectures where TASK_SIZE is greater than SIZE_MAX-PAGE_SIZE

    The patch is from David S. Miller, not me. My patch was
incomplete and did nothing on 'big TASK_SIZE' architectures, as
sparc64.

    The patch is against both 2.4.20 and 2.4.21-pre1, is just the same.

    Raúl

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--- linux/mm/mmap.c.orig	2002-12-11 13:59:37.000000000 +0100
+++ linux/mm/mmap.c	2002-12-11 14:01:16.000000000 +0100
@@ -403,10 +403,12 @@
 	if (file && (!file->f_op || !file->f_op->mmap))
 		return -ENODEV;
 
-	if ((len = PAGE_ALIGN(len)) == 0)
+	if (!len)
 		return addr;
 
-	if (len > TASK_SIZE)
+	len = PAGE_ALIGN(len);
+
+	if (len > TASK_SIZE || len == 0)
 		return -EINVAL;
 
 	/* offset overflow? */