Commit 1b1f693d authored Oct 28, 2010 by Linus Torvalds Committed by David S. Miller Oct 30, 2010

net: fix rds_iovec page count overflow



As reported by Thomas Pollet, the rdma page counting can overflow.  We
get the rdma sizes in 64-bit unsigned entities, but then limit it to
UINT_MAX bytes and shift them down to pages (so with a possible "+1" for
an unaligned address).

So each individual page count fits comfortably in an 'unsigned int' (not
even close to overflowing into signed), but as they are added up, they
might end up resulting in a signed return value. Which would be wrong.

Catch the case of tot_pages turning negative, and return the appropriate
error code.

Reported-by: Thomas Pollet <thomas.pollet@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent bdfa3d8f

net/rds/rdma.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -502,6 +502,13 @@ static int rds_rdma_pages(struct rds_rdma_args *args)
		return -EINVAL;

		tot_pages += nr_pages;

		/*
		* nr_pages for one entry is limited to (UINT_MAX>>PAGE_SHIFT)+1,
		* so tot_pages cannot overflow without first going negative.
		*/
		if ((int)tot_pages < 0)
		return -EINVAL;
		}

		return tot_pages;

Admin message