Commit 49e186e3 authored Nov 02, 2017 by David Howells Committed by Greg Kroah-Hartman Dec 14, 2017

afs: Fix total-length calculation for multiple-page send




[ Upstream commit 1199db60 ]

Fix the total-length calculation in afs_make_call() when the operation
being dispatched has data from a series of pages attached.

Despite the patched code looking like that it should reduce mathematically
to the current code, it doesn't because the 32-bit unsigned arithmetic
being used to calculate the page-offset-difference doesn't correctly extend
to a 64-bit value when the result is effectively negative.

Without this, some FS.StoreData operations that span multiple pages fail,
reporting too little or too much data.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent d702be10

fs/afs/rxrpc.c

+11 −2

Original line number	Original line	Diff line number	Diff line
	@@ -377,8 +377,17 @@ int afs_make_call(struct in_addr addr, struct afs_call call, gfp_t gfp,
	*/		*/
	tx_total_len = call->request_size;		tx_total_len = call->request_size;
	if (call->send_pages) {		if (call->send_pages) {
			if (call->last == call->first) {
	tx_total_len += call->last_to - call->first_offset;		tx_total_len += call->last_to - call->first_offset;
	tx_total_len += (call->last - call->first) * PAGE_SIZE;		} else {
			/* It looks mathematically like you should be able to
			* combine the following lines with the ones above, but
			* unsigned arithmetic is fun when it wraps...
			*/
			tx_total_len += PAGE_SIZE - call->first_offset;
			tx_total_len += call->last_to;
			tx_total_len += (call->last - call->first - 1) * PAGE_SIZE;
			}
	}		}

	/* create a call */		/* create a call */