From 641543b76b82a8b361482b727e08de0c8ec093b0 Mon Sep 17 00:00:00 2001 From: Stefan Weil Date: Sat, 21 Jan 2012 13:54:24 +0100 Subject: block/vdi: Zero unused parts when allocating a new block (fix #919242) The new block was filled with zero when it was allocated by g_malloc0, but when it was reused later and only partially used, data from the previously allocated block were still present and written to the new block. This caused the problems reported by bug #919242 (https://bugs.launchpad.net/qemu/+bug/919242). Now the unused parts of the new block which are before and after the data are always filled with zero, so it is no longer necessary to zero the whole block with g_malloc0. I also updated the copyright comment. Signed-off-by: Stefan Weil Signed-off-by: Kevin Wolf --- block/vdi.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'block') diff --git a/block/vdi.c b/block/vdi.c index 31cdfabdea..6a0011fbcc 100644 --- a/block/vdi.c +++ b/block/vdi.c @@ -1,7 +1,7 @@ /* * Block driver for the Virtual Disk Image (VDI) format * - * Copyright (c) 2009 Stefan Weil + * Copyright (c) 2009, 2012 Stefan Weil * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -756,15 +756,19 @@ static void vdi_aio_write_cb(void *opaque, int ret) (uint64_t)bmap_entry * s->block_sectors; block = acb->block_buffer; if (block == NULL) { - block = g_malloc0(s->block_size); + block = g_malloc(s->block_size); acb->block_buffer = block; acb->bmap_first = block_index; assert(!acb->header_modified); acb->header_modified = 1; } acb->bmap_last = block_index; + /* Copy data to be written to new block and zero unused parts. */ + memset(block, 0, sector_in_block * SECTOR_SIZE); memcpy(block + sector_in_block * SECTOR_SIZE, acb->buf, n_sectors * SECTOR_SIZE); + memset(block + (sector_in_block + n_sectors) * SECTOR_SIZE, 0, + (s->block_sectors - n_sectors - sector_in_block) * SECTOR_SIZE); acb->hd_iov.iov_base = (void *)block; acb->hd_iov.iov_len = s->block_size; qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1); -- cgit v1.2.3