From: Mike Frysinger <vapier@gentoo.org>
Date: Wed, 6 Dec 2006 02:02:59 +0000 (+1000)
Subject: [PATCH] uclinux: fix mmap() of directory for nommu case
X-Git-Tag: v2.6.20-rc1~34^2~20^2~34
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f81cff0d4067e41fd7383d9c013cc82da7c169d2;p=linux-2.6

[PATCH] uclinux: fix mmap() of directory for nommu case

I was playing with blackfin when i hit a neat bug ... doing an open() on a
directory and then passing that fd to mmap() would cause the kernel to hang

after poking into the code a bit more, i found that
mm/nommu.c:validate_mmap_request() checks the length and if it is 0, just
returns the address ... this is in stark contrast to mmu's
mm/mmap.c:do_mmap_pgoff() where it returns -EINVAL for 0 length requests ...
i then noticed that some other parts of the logic is out of date between the
two funcs, so perhaps that's the easy fix ?

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/mm/nommu.c b/mm/nommu.c
index 8bdde9508f..6a2a8aada4 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -497,15 +497,17 @@ static int validate_mmap_request(struct file *file,
 	    (flags & MAP_TYPE) != MAP_SHARED)
 		return -EINVAL;
 
-	if (PAGE_ALIGN(len) == 0)
-		return addr;
-
-	if (len > TASK_SIZE)
+	if (!len)
 		return -EINVAL;
 
+	/* Careful about overflows.. */
+	len = PAGE_ALIGN(len);
+	if (!len || len > TASK_SIZE)
+		return -ENOMEM;
+
 	/* offset overflow? */
 	if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
-		return -EINVAL;
+		return -EOVERFLOW;
 
 	if (file) {
 		/* validate file mapping requests */