Re: [PATCH] lxc: fix lxcContainerMountAllFS() DEREF_BEFORE_CHECK

On Wed, Sep 06, 2023 at 06:34:42PM +0300, Dmitry Frolov wrote: > Reviewing the sources, I found, that > in function lxcContainerMountAllFS() pointers > vmDef->fss[i]->src and vmDef->fss[i]->src->path > are checked for NULL after dereferencing in > VIR_DEBUG() macro. > > Fixes: 57487085dc ("lxc: don't try to reference NULL when mounting filesystems") > --- > src/lxc/lxc_container.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-)

> if (lxcContainerResolveSymlinks(vmDef->fss[i], false) < 0) > return -1; > > - if (!(vmDef->fss[i]->src && vmDef->fss[i]->src->path && > - STRPREFIX(vmDef->fss[i]->src->path, vmDef->fss[i]->dst)) && > + if (!STRPREFIX(vmDef->fss[i]->src->path, vmDef->fss[i]->dst) && > lxcContainerUnmountSubtree(vmDef->fss[i]->dst, false) < 0) ... here it only skips the unmount in such case. That makes sense because for example tmpfs does not have a source path, only the destination and the mount that is not visible in the context here would not only be skipped as well, but the whole starting of a domain would fail. Instead of this patch, you could just conditionally change the VIR_DEBUG() to report what's actually happening.

> return -1; > > -- > 2.34.1 >