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nommu: check fd read permission in validate_mmap_request()

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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>
This commit is contained in:
Graff Yang 2009-08-18 14:11:17 -07:00 • committed by Linus Torvalds
commit 28d7a6ae92
1 changed files with 4 additions and 0 deletions
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4
mm/nommu.c
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@ -919,6 +919,10 @@ static int validate_mmap_request(struct file *file,
if (!file->f_op->read) if (!file->f_op->read)
capabilities &= ~BDI_CAP_MAP_COPY; 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) { if (flags & MAP_SHARED) {
/* do checks for writing, appending and locking */ /* do checks for writing, appending and locking */
if ((prot & PROT_WRITE) && if ((prot & PROT_WRITE) &&