[PATCH] virDevMapperGetTargetsImpl: quit early if device is not a devmapper target

As suggested in the linked bug, libvirt should firstly check whether the major number of the device is device mapper major. Because if it isn't subsequent DM_DEVICE_DEPS task may not only fail, but also yield different results. In the bugzilla this is demonstrated by creating a devmapper target named 'loop0' and then creating loop target /dev/loop0. When the latter is then passed to a domain, our virDevMapperGetTargetsImpl() function blindly asks devmapper to provide target dependencies for /dev/loop0 and because of the way devmapper APIs work, it will 'sanitize' the input by using the last component only which is 'loop0' and thus return different results than expected. Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1823976 Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/util/virdevmapper.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/src/util/virdevmapper.c b/src/util/virdevmapper.c index feb5982315..ee026d502e 100644 --- a/src/util/virdevmapper.c +++ b/src/util/virdevmapper.c @@ -64,6 +64,7 @@ virDevMapperGetTargetsImpl(const char *path, char ***devPaths_ret, unsigned int ttl) { + struct stat sb; struct dm_task *dmt = NULL; struct dm_deps *deps; struct dm_info info; @@ -82,6 +83,15 @@ virDevMapperGetTargetsImpl(const char *path, return ret; } + if (stat(path, &sb) < 0) { + if (errno == ENOENT) + ret = 0; + return ret; + } + + if (!dm_is_dm_major(major(sb.st_dev))) + return 0; + if (!(dmt = dm_task_create(DM_DEVICE_DEPS))) { if (errno == ENOENT || errno == ENODEV) { /* It's okay. Kernel is probably built without -- 2.26.2