Commit d2da5b0c authored Oct 23, 2013 by Lars Ellenberg Committed by Jens Axboe Nov 08, 2013

drbd: fix decoding of bitmap vli rle for device sizes > 64 TB



Symptoms: disconnect after bitmap exchange due to
bitmap overflow (e:49731075554) while decoding bm RLE packet

In the decoding step of the variable length integer run length encoding
there was potentially an uncatched bitshift by wordsize (variable >> 64).

The result of which is "undefined" :(
(only "sometimes" the result is the desired 0)

Fix: don't do any bit shift magic for shift == 64, just assign.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent 57737adc

drivers/block/drbd/drbd_receiver.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -4125,7 +4125,11 @@ recv_bm_rle_bits(struct drbd_conf *mdev,
		(unsigned int)bs.buf_len);
		return -EIO;
		}
		/* if we consumed all 64 bits, assign 0; >> 64 is "undefined"; */
		if (likely(bits < 64))
		look_ahead >>= bits;
		else
		look_ahead = 0;
		have -= bits;

		bits = bitstream_get_bits(&bs, &tmp, 64 - have);