[libvirt] [PATCH] storage: fix memory leak with encrypted images

Jim Fehlig reported a regression found by libvirt-TCK tests: ... Commit 2279d560 converted a boolean into a pointer with the intent of transferring that pointer out of a temporary object into the caller's data structure. The temporary structure meant that meta->encryption was always NULL on entry, so we could get away with blindly allocating the pointer when the header said so. But later commits then tweaked things to do backing chain detection in-place, rather than via a temporary object; this has the net result that meta->encryption can be non-NULL on entry. Not only did this turn the latent behavior into a memory leak, it is also a behavior regression: blindly allocating a new pointer wipes out what secrets we already knew about the chain, making it impossible to restart the domain. Of course, no one in their right mind should be relying on qcow2 encryption - it is fundamentally flawed. And sadly, the TCK tests don't get run often enough, and this shows that our virstoragetest does not exercise encrypted images at all. Otherwise, we could have avoided a release containing this regression. * src/util/virstoragefile.c (virStorageFileGetMetadataInternal): Don't nuke an already-existing encryption. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- src/util/virstoragefile.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/util/virstoragefile.c b/src/util/virstoragefile.c index 43b7a5a..0792dd8 100644 --- a/src/util/virstoragefile.c +++ b/src/util/virstoragefile.c @@ -805,7 +805,8 @@ virStorageFileGetMetadataInternal(virStorageSourcePtr meta, crypt_format = virReadBufInt32BE(buf + fileTypeInfo[meta->format].qcowCryptOffset); - if (crypt_format && VIR_ALLOC(meta->encryption) < 0) + if (crypt_format && !meta->encryption && + VIR_ALLOC(meta->encryption) < 0) goto cleanup; } -- 1.9.3