VHD files technically can be up to 2Tb, but virtual pc is limited to 127G. Currently qemu-img refused to create vpc files > 127G, but it is failing to return error when converting from a non-vpc VHD file which is >127G. It returns success, but creates a truncated converted image. Also, qemu-img info claims the vpc file is 127G (and clean).
This patch detects a too-large vpc file and returns -EFBIG. Without this patch, ============================================================= root@ip-10-38-123-242:~/qemu-fixed# qemu-img info /mnt/140g-dynamic.vhd image: /mnt/140g-dynamic.vhd file format: vpc virtual size: 127G (136899993600 bytes) disk size: 284K root@ip-10-38-123-242:~/qemu-fixed# qemu-img convert -f vpc -O raw /mnt/140g-dynamic.vhd /mnt/y root@ip-10-38-123-242:~/qemu-fixed# echo $? 0 root@ip-10-38-123-242:~/qemu-fixed# qemu-img info /mnt/y image: /mnt/y file format: raw virtual size: 127G (136899993600 bytes) disk size: 0 ============================================================= (The 140G image was truncated with no warning or error.) With the patch, I get: ============================================================= root@ip-10-38-123-242:~/qemu-fixed# ./qemu-img info /mnt/140g-dynamic.vhd qemu-img: Could not open '/mnt/140g-dynamic.vhd': File too large root@ip-10-38-123-242:~/qemu-fixed# ./qemu-img convert -f vpc -O raw /mnt/140g-dynamic.vhd /mnt/y qemu-img: Could not open '/mnt/140g-dynamic.vhd': File too large qemu-img: Could not open '/mnt/140g-dynamic.vhd' ============================================================= See https://bugs.launchpad.net/qemu/+bug/814222 for details. Signed-off-by: Serge Hallyn <serge.hal...@canonical.com> --- block/vpc.c | 8 +++++++- 1 files changed, 7 insertions(+), 1 deletions(-) diff --git a/block/vpc.c b/block/vpc.c index 56865da..fdd5236 100644 --- a/block/vpc.c +++ b/block/vpc.c @@ -156,6 +156,7 @@ static int vpc_open(BlockDriverState *bs, int flags) struct vhd_dyndisk_header* dyndisk_header; uint8_t buf[HEADER_SIZE]; uint32_t checksum; + int err = -1; if (bdrv_pread(bs->file, 0, s->footer_buf, HEADER_SIZE) != HEADER_SIZE) goto fail; @@ -176,6 +177,11 @@ static int vpc_open(BlockDriverState *bs, int flags) bs->total_sectors = (int64_t) be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl; + if (bs->total_sectors >= 65535 * 16 * 255) { + err = -EFBIG; + goto fail; + } + if (bdrv_pread(bs->file, be64_to_cpu(footer->data_offset), buf, HEADER_SIZE) != HEADER_SIZE) goto fail; @@ -222,7 +228,7 @@ static int vpc_open(BlockDriverState *bs, int flags) return 0; fail: - return -1; + return err; } /* -- 1.7.5.4
