diff options
author | Peter Feiner <peter@gridcentric.ca> | 2014-01-08 19:43:25 +0000 |
---|---|---|
committer | Kevin Wolf <kwolf@redhat.com> | 2014-01-22 13:47:52 +0100 |
commit | d80ac658f2caacfb14ea386211c4a9bea0cea280 (patch) | |
tree | c2eea663d2e7f9e7173cbe880c0064475a3c7858 | |
parent | 91f84f652de14329d5ad0666499a78fd0db0f1c7 (diff) |
block: fix backing file segfault
When a backing file is opened such that (1) a protocol is directly
used as the block driver and (2) the block driver has bdrv_file_open,
bdrv_open_backing_file segfaults. The problem arises because
bdrv_open_common returns without setting bd->backing_hd->file.
To effect (1), you seem to have to use the -F flag in qemu-img. There
are several block drivers that satisfy (2), such as "file" and "nbd".
Here are some concrete examples:
#!/bin/bash
echo Test file format
./qemu-img create -f file base.file 1m
./qemu-img create -f qcow2 -F file -o backing_file=base.file\
file-overlay.qcow2
./qemu-img convert -O raw file-overlay.qcow2 file-convert.raw
echo Test nbd format
SOCK=$PWD/nbd.sock
./qemu-img create -f raw base.raw 1m
./qemu-nbd -t -k $SOCK base.raw &
trap "kill $!" EXIT
while ! test -e $SOCK; do sleep 1; done
./qemu-img create -f qcow2 -F nbd -o backing_file=nbd:unix:$SOCK\
nbd-overlay.qcow2
./qemu-img convert -O raw nbd-overlay.qcow2 nbd-convert.raw
Without this patch, the two qemu-img convert commands segfault.
This is a regression that was introduced in v1.7 by
dbecebddfa4932d1c83915bcb9b5ba5984eb91be.
Signed-off-by: Peter Feiner <peter@gridcentric.ca>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
-rw-r--r-- | block.c | 8 |
1 files changed, 6 insertions, 2 deletions
@@ -1040,8 +1040,12 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp) error_free(local_err); return ret; } - pstrcpy(bs->backing_file, sizeof(bs->backing_file), - bs->backing_hd->file->filename); + + if (bs->backing_hd->file) { + pstrcpy(bs->backing_file, sizeof(bs->backing_file), + bs->backing_hd->file->filename); + } + return 0; } |