Commit 5ec1055a authored Sep 24, 2010 by Larry Woodman Committed by Linus Torvalds Sep 25, 2010

Avoid pgoff overflow in remap_file_pages



Thomas Pollet noticed that the remap_file_pages() system call in
fremap.c has a potential overflow in the first part of the if statement
below, which could cause it to process bogus input parameters.
Specifically the pgoff + size parameters could be wrap thereby
preventing the system call from failing when it should.

Reported-by: Thomas Pollet <thomas.pollet@gmail.com>
Signed-off-by: Larry Woodman <lwoodman@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 8ae09259

mm/fremap.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -141,6 +141,10 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
		if (start + size <= start)
		return err;

		/* Does pgoff wrap? */
		if (pgoff + (size >> PAGE_SHIFT) < pgoff)
		return err;

		/* Can we represent this offset inside this architecture's pte's? */
		#if PTE_FILE_MAX_BITS < BITS_PER_LONG
		if (pgoff + (size >> PAGE_SHIFT) >= (1UL << PTE_FILE_MAX_BITS))

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