On Tue, Dec 04, 2018 at 05:34:08PM -0800, Nadav Amit wrote: > 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. Fun detail, only x86 seems to actually take text_mutex while poking text. > Signed-off-by: Nadav Amit <namit@xxxxxxxxxx> > --- > kernel/module.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/kernel/module.c b/kernel/module.c > index 57c5b23746e7..b45754961143 100644 > --- a/kernel/module.c > +++ b/kernel/module.c > @@ -64,6 +64,7 @@ > #include <linux/bsearch.h> > #include <linux/dynamic_debug.h> > #include <linux/audit.h> > +#include <linux/memory.h> > #include <uapi/linux/module.h> > #include "module-internal.h" > > @@ -2181,6 +2182,9 @@ static void free_module(struct module *mod) > synchronize_sched(); > 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_restore_mappings(&mod->init_layout); > module_arch_freeing_init(mod); > @@ -2194,6 +2198,7 @@ static void free_module(struct module *mod) > /* Finally, free the core (containing the module structure) */ > module_restore_mappings(&mod->core_layout); > module_memfree(mod->core_layout.base); > + mutex_unlock(&text_mutex); > } > > void *__symbol_get(const char *symbol) > -- > 2.17.1 >
