From b0ce8cb0e8470b37963d1db7e4baca9c3647b0a1 Mon Sep 17 00:00:00 2001 From: Markus Armbruster Date: Thu, 17 Dec 2020 17:19:56 +0100 Subject: [PATCH] block/vpc: Don't abuse the footer buffer as BAT sector buffer create_dynamic_disk() takes a buffer holding the footer as first argument. It writes out the footer (512 bytes), then reuses the buffer to initialize and write out the dynamic header (1024 bytes), then reuses it again to initialize and write out BAT sectors (512). Works, because the caller passes a buffer that is large enough for all three purposes. I hate that. Use a separate buffer for writing out BAT sectors. The next commit will do the same for the dynamic header. Signed-off-by: Markus Armbruster Message-Id: <20201217162003.1102738-3-armbru@redhat.com> Reviewed-by: Max Reitz Signed-off-by: Kevin Wolf --- block/vpc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/block/vpc.c b/block/vpc.c index 2fcf3f6283..d18ecc3da1 100644 --- a/block/vpc.c +++ b/block/vpc.c @@ -824,6 +824,7 @@ static int create_dynamic_disk(BlockBackend *blk, uint8_t *buf, { VHDDynDiskHeader *dyndisk_header = (VHDDynDiskHeader *) buf; + uint8_t bat_sector[512]; size_t block_size, num_bat_entries; int i; int ret; @@ -847,9 +848,9 @@ static int create_dynamic_disk(BlockBackend *blk, uint8_t *buf, /* Write the initial BAT */ offset = 3 * 512; - memset(buf, 0xFF, 512); + memset(bat_sector, 0xFF, 512); for (i = 0; i < DIV_ROUND_UP(num_bat_entries * 4, 512); i++) { - ret = blk_pwrite(blk, offset, buf, 512, 0); + ret = blk_pwrite(blk, offset, bat_sector, 512, 0); if (ret < 0) { goto fail; }