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

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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>
This commit is contained in:
Lars Ellenberg 2013-10-23 10:59:18 +02:00 committed by Jens Axboe
parent 57737adc96
commit d2da5b0cb5
1 changed files with 5 additions and 1 deletions
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6
drivers/block/drbd/drbd_receiver.c
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@ -4125,7 +4125,11 @@ recv_bm_rle_bits(struct drbd_conf *mdev,
(unsigned int)bs.buf_len); (unsigned int)bs.buf_len);
return -EIO; return -EIO;
} }
look_ahead >>= bits; /* if we consumed all 64 bits, assign 0; >> 64 is "undefined"; */
if (likely(bits < 64))
look_ahead >>= bits;
else
look_ahead = 0;
have -= bits; have -= bits;
bits = bitstream_get_bits(&bs, &tmp, 64 - have); bits = bitstream_get_bits(&bs, &tmp, 64 - have);