On Fri, 18 Sep 2026, Miroslav Benes wrote: > On Tue, 8 Sep 2026, Petr Mladek wrote: > > > When a module is loaded, klp_module_coming() updates all enabled > > livepatches. If an error occurs, it delegates cleanup to > > klp_cleanup_module_patches_limited(). However, this cleanup loop skips > > the partially updated patch, leaving any changes made prior to failure > > unreverted. > > > > One unhandled failure path occurs inside klp_apply_object_relocs(). On > > architectures like x86_64, apply_relocate_add() performs a verification > > step using memcmp() to check that memory contains the expected relocated > > or zeroed value. If relocations left behind by a failed patch are not > > cleared, subsequent patch operations or reloads can fail this validation. > > > > Introduce klp_write_object_relocs_limited() to unwind and clear only the > > relocations that were successfully applied before klp_write_object_relocs() > > encountered an error. > > > > There is no need to clear relocations for other objects in the failing > > patch because klp_module_coming() operates strictly on the specific > > module being loaded. > > Hm, I spent some quite time on that and I am not sure if I deciphered > everything correctly. > > It seems to me that all error handling in those paths you are mentioning > above is correct and the only problematic thing is that > klp_apply_object_relocs() in klp_init_object_loaded() returns ret > immediately which leaves partially applied relocations in case of an > error. Following calls in klp_init_object_loaded() go through err: label > where klp_free_object_loaded() is called which should be fine. > > Is it correct? > > Wouldn't be better to be somehow consistent and clean up right in the > error path of klp_apply_object_relocs() call in klp_init_object_loaded() > similarly to what is already there. After all we want to clean the object. > > But I also see why you want to do it this way. It only seems more fragile > to me.
And only now I realized that I checked with 5/5 already applied by mistake. The above still stands though and at least I reviewed 5/5 as well. Miroslav
