From: Graff Yang <graff.yang@gmail.com>
Date: Tue, 18 Aug 2009 21:11:17 +0000 (-0700)
Subject: nommu: check fd read permission in validate_mmap_request()
X-Git-Tag: v2.6.31-rc7~19
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=28d7a6ae92c099d81cbea08c20be0d2cf7ccd7ca;p=linux.git

nommu: check fd read permission in validate_mmap_request()

According to the POSIX (1003.1-2008), the file descriptor shall have been
opened with read permission, regardless of the protection options specified to
mmap().  The ltp test cases mmap06/07 need this.

Signed-off-by: Graff Yang <graff.yang@gmail.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Greg Ungerer <gerg@snapgear.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/nommu.c b/mm/nommu.c
index 28754c40be98..4bde489ec431 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -919,6 +919,10 @@ static int validate_mmap_request(struct file *file,
 		if (!file->f_op->read)
 			capabilities &= ~BDI_CAP_MAP_COPY;
 
+		/* The file shall have been opened with read permission. */
+		if (!(file->f_mode & FMODE_READ))
+			return -EACCES;
+
 		if (flags & MAP_SHARED) {
 			/* do checks for writing, appending and locking */
 			if ((prot & PROT_WRITE) &&