From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rick Edgecombe Subject: [PATCH 17/17] module: Prevent module removal racing with text_poke() Date: Wed, 16 Jan 2019 16:32:59 -0800 Message-Id: <20190117003259.23141-18-rick.p.edgecombe@intel.com> In-Reply-To: <20190117003259.23141-1-rick.p.edgecombe@intel.com> References: <20190117003259.23141-1-rick.p.edgecombe@intel.com> To: Andy Lutomirski , Ingo Molnar Cc: linux-kernel@vger.kernel.org, x86@kernel.org, hpa@zytor.com, Thomas Gleixner , Borislav Petkov , Nadav Amit , Dave Hansen , Peter Zijlstra , linux_dti@icloud.com, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, akpm@linux-foundation.org, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, will.deacon@arm.com, ard.biesheuvel@linaro.org, kristen@linux.intel.com, deneen.t.dock@intel.com, Nadav Amit , Rick Edgecombe List-ID: From: Nadav Amit It seems dangerous to allow code modifications to take place concurrently with module unloading. So take the text_mutex while the memory of the module is freed. Signed-off-by: Nadav Amit Signed-off-by: Rick Edgecombe --- kernel/module.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/module.c b/kernel/module.c index 1af5c8e19086..90cfc4988d98 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -64,6 +64,7 @@ #include #include #include +#include #include #include "module-internal.h" @@ -2157,6 +2158,9 @@ static void free_module(struct module *mod) synchronize_rcu(); mutex_unlock(&module_mutex); + /* Protect against patching of the module while it is being removed */ + mutex_lock(&text_mutex); + /* This may be empty, but that's OK */ module_arch_freeing_init(mod); module_memfree(mod->init_layout.base); @@ -2168,6 +2172,7 @@ static void free_module(struct module *mod) /* Finally, free the core (containing the module structure) */ module_memfree(mod->core_layout.base); + mutex_unlock(&text_mutex); } void *__symbol_get(const char *symbol) -- 2.17.1