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Tue, 30 Jun 2026 08:50:23 -0700 (PDT) Date: Tue, 30 Jun 2026 17:50:21 +0200 From: Petr Mladek To: Yafang Shao Cc: mbenes@suse.cz, jikos@kernel.org, joe.lawrence@redhat.com, jpoimboe@kernel.org, live-patching@vger.kernel.org, sashiko-bot@kernel.org, song@kernel.org Subject: Re: [PATCH v2] livepatch: Fix NULL pointer dereference in klp_find_func() Message-ID: References: <20260628114635.33572-1-laoar.shao@gmail.com> Precedence: bulk X-Mailing-List: live-patching@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260628114635.33572-1-laoar.shao@gmail.com> On Sun 2026-06-28 19:46:35, Yafang Shao wrote: > A NULL old_name in a newly loaded livepatch's function entry causes a > NULL pointer dereference in strcmp(): > > klp_init_patch() > klp_add_nops() > klp_find_func() > strcmp(old_func->old_name, func->old_name) > > Add klp_check_patch() at the beginning of klp_enable_patch() to reject > patches with NULL old_name before they reach this code path. > > Reported-by: sashiko-bot > Closes: https://lore.kernel.org/live-patching/20260529040130.95A9C1F00893@smtp.kernel.org/ > Suggested-by: Petr Mladek > Suggested-by: Miroslav Benes > Signed-off-by: Yafang Shao > Acked-by: Miroslav Benes Looks good to me: Reviewed-by: Petr Mladek Tested-by: Petr Mladek I think whether to rush this into 7.2-rcX or wait for 7.3. On one hand, it is a possible security fix. On the other hand, broken module could never get loaded and pass even a minimal QA. I tend to push it for 7.2-rcX just to avoid questions from people who ignore the real life vulnerabilty aspect. Also see a nit below. > --- a/kernel/livepatch/core.c > +++ b/kernel/livepatch/core.c > @@ -1092,6 +1089,25 @@ static int __klp_enable_patch(struct klp_patch *patch) > return ret; > } > > +static int klp_check_patch(struct klp_patch *patch) > +{ > + struct klp_object *obj; > + struct klp_func *func; > + > + if (!patch || !patch->mod || !patch->objs) > + return -EINVAL; > + > + klp_for_each_object_static(patch, obj) { > + if (!obj->funcs) > + return -EINVAL; Nit: I would add an empty line here to make it better readable. Of course, this is a personal preference. But it seems that most contributors to this code prefer visual separators between misc code sections as well. No need for v3. I could add the empty line when pushing the change. > + klp_for_each_func_static(obj, func) { > + if (!func->old_name) > + return -EINVAL; > + } > + } > + return 0; > +} > + > /** > * klp_enable_patch() - enable the livepatch > * @patch: patch to be enabled Best Regards, Petr