Commit 65c61de9 authored Apr 30, 2021 by Linus Torvalds

linux

Pull module updates from Jessica Yu:
 "Fix an age old bug involving jump_calls and static_labels when
  CONFIG_MODULE_UNLOAD=n.

  When CONFIG_MODULE_UNLOAD=n, it means you can't unload modules, so
  normally the __exit sections of a module are not loaded at all.
  However, dynamic code patching (jump_label, static_call, alternatives)
  can have sites in __exit sections even if __exit is never executed.

  Reported by Peter Zijlstra:
     'Alternatives, jump_labels and static_call all can have relocations
      into __exit code. Not loading it at all would be BAD.'

  Therefore, load the __exit sections even when CONFIG_MODULE_UNLOAD=n,
  and discard them after init"

* tag 'modules-for-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
  module: treat exit sections the same as init sections when !CONFIG_MODULE_UNLOAD

parents c70a4be1 33121347

kernel/module.c

+4 −5

Original line number	Diff line number	Diff line
		@@ -2807,7 +2807,11 @@ void * __weak module_alloc(unsigned long size)

		bool __weak module_init_section(const char *name)
		{
		#ifndef CONFIG_MODULE_UNLOAD
		return strstarts(name, ".init") \|\| module_exit_section(name);
		#else
		return strstarts(name, ".init");
		#endif
		}

		bool __weak module_exit_section(const char *name)
		@@ -3121,11 +3125,6 @@ static int rewrite_section_headers(struct load_info *info, int flags)
		*/
		shdr->sh_addr = (size_t)info->hdr + shdr->sh_offset;

		#ifndef CONFIG_MODULE_UNLOAD
		/* Don't load .exit sections */
		if (module_exit_section(info->secstrings+shdr->sh_name))
		shdr->sh_flags &= ~(unsigned long)SHF_ALLOC;
		#endif
		}

		/* Track but don't keep modinfo and version sections. */