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Commit 65b8a9b4 authored by Linus Torvalds's avatar Linus Torvalds Committed by Rusty Russell
Browse files

module: refactor load_module part 2 



Here's a second one. It's slightly less trivial - since we now have error
cases - and equally untested so it may well be totally broken. But it also
cleans up a bit more, and avoids one of the goto targets, because the
"move_module()" helper now does both allocations or none.

Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent f91a13bb

kernel/module.c

+72 −57
Original line number Diff line number Diff line
@@ -2082,7 +2082,8 @@ static void *module_alloc_update_bounds(unsigned long size) 


#ifdef CONFIG_DEBUG_KMEMLEAK

static void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr,

				 Elf_Shdr *sechdrs, char *secstrings)

				 const Elf_Shdr *sechdrs,

				 const char *secstrings)

{

	unsigned int i;
@@ -2102,7 +2103,8 @@ static void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr, 
}

#else

static inline void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr,

					Elf_Shdr *sechdrs, char *secstrings)

					Elf_Shdr *sechdrs,

					const char *secstrings)

{

}

#endif
@@ -2172,6 +2174,70 @@ static void find_module_sections(struct module *mod, Elf_Ehdr *hdr, 
#endif

}



static struct module *move_module(struct module *mod,

				  Elf_Ehdr *hdr, Elf_Shdr *sechdrs,

				  const char *secstrings, unsigned modindex)

{

	int i;

	void *ptr;



	/* Do the allocs. */

	ptr = module_alloc_update_bounds(mod->core_size);

	/*

	 * The pointer to this block is stored in the module structure

	 * which is inside the block. Just mark it as not being a

	 * leak.

	 */

	kmemleak_not_leak(ptr);

	if (!ptr)

		return ERR_PTR(-ENOMEM);



	memset(ptr, 0, mod->core_size);

	mod->module_core = ptr;



	ptr = module_alloc_update_bounds(mod->init_size);

	/*

	 * The pointer to this block is stored in the module structure

	 * which is inside the block. This block doesn't need to be

	 * scanned as it contains data and code that will be freed

	 * after the module is initialized.

	 */

	kmemleak_ignore(ptr);

	if (!ptr && mod->init_size) {

		module_free(mod, mod->module_core);

		return ERR_PTR(-ENOMEM);

	}

	memset(ptr, 0, mod->init_size);

	mod->module_init = ptr;



	/* Transfer each section which specifies SHF_ALLOC */

	DEBUGP("final section addresses:\n");

	for (i = 0; i < hdr->e_shnum; i++) {

		void *dest;



		if (!(sechdrs[i].sh_flags & SHF_ALLOC))

			continue;



		if (sechdrs[i].sh_entsize & INIT_OFFSET_MASK)

			dest = mod->module_init

				+ (sechdrs[i].sh_entsize & ~INIT_OFFSET_MASK);

		else

			dest = mod->module_core + sechdrs[i].sh_entsize;



		if (sechdrs[i].sh_type != SHT_NOBITS)

			memcpy(dest, (void *)sechdrs[i].sh_addr,

			       sechdrs[i].sh_size);

		/* Update sh_addr to point to copy in image. */

		sechdrs[i].sh_addr = (unsigned long)dest;

		DEBUGP("\t0x%lx %s\n",

		       sechdrs[i].sh_addr, secstrings + sechdrs[i].sh_name);

	}

	/* Module has been moved. */

	mod = (void *)sechdrs[modindex].sh_addr;

	kmemleak_load_module(mod, hdr, sechdrs, secstrings);

	return mod;

}



/* Allocate and load the module: note that size of section 0 is always

   zero, and we rely on this for optional sections. */

static noinline struct module *load_module(void __user *umod,
@@ -2188,7 +2254,6 @@ static noinline struct module *load_module(void __user *umod, 
	unsigned int modindex, versindex, infoindex, pcpuindex;

	struct module *mod;

	long err = 0;

	void *ptr = NULL; /* Stops spurious gcc warning */

	unsigned long symoffs, stroffs, *strmap;

	void __percpu *percpu;

	struct _ddebug *debug = NULL;
@@ -2342,61 +2407,12 @@ static noinline struct module *load_module(void __user *umod, 
	symoffs = layout_symtab(mod, sechdrs, symindex, strindex, hdr,

				secstrings, &stroffs, strmap);



	/* Do the allocs. */

	ptr = module_alloc_update_bounds(mod->core_size);

	/*

	 * The pointer to this block is stored in the module structure

	 * which is inside the block. Just mark it as not being a

	 * leak.

	 */

	kmemleak_not_leak(ptr);

	if (!ptr) {

		err = -ENOMEM;

	/* Allocate and move to the final place */

	mod = move_module(mod, hdr, sechdrs, secstrings, modindex);

	if (IS_ERR(mod)) {

		err = PTR_ERR(mod);

		goto free_percpu;

	}

	memset(ptr, 0, mod->core_size);

	mod->module_core = ptr;



	ptr = module_alloc_update_bounds(mod->init_size);

	/*

	 * The pointer to this block is stored in the module structure

	 * which is inside the block. This block doesn't need to be

	 * scanned as it contains data and code that will be freed

	 * after the module is initialized.

	 */

	kmemleak_ignore(ptr);

	if (!ptr && mod->init_size) {

		err = -ENOMEM;

		goto free_core;

	}

	memset(ptr, 0, mod->init_size);

	mod->module_init = ptr;



	/* Transfer each section which specifies SHF_ALLOC */

	DEBUGP("final section addresses:\n");

	for (i = 0; i < hdr->e_shnum; i++) {

		void *dest;



		if (!(sechdrs[i].sh_flags & SHF_ALLOC))

			continue;



		if (sechdrs[i].sh_entsize & INIT_OFFSET_MASK)

			dest = mod->module_init

				+ (sechdrs[i].sh_entsize & ~INIT_OFFSET_MASK);

		else

			dest = mod->module_core + sechdrs[i].sh_entsize;



		if (sechdrs[i].sh_type != SHT_NOBITS)

			memcpy(dest, (void *)sechdrs[i].sh_addr,

			       sechdrs[i].sh_size);

		/* Update sh_addr to point to copy in image. */

		sechdrs[i].sh_addr = (unsigned long)dest;

		DEBUGP("\t0x%lx %s\n",

		       sechdrs[i].sh_addr, secstrings + sechdrs[i].sh_name);

	}

	/* Module has been moved. */

	mod = (void *)sechdrs[modindex].sh_addr;

	kmemleak_load_module(mod, hdr, sechdrs, secstrings);



#if defined(CONFIG_MODULE_UNLOAD)

	mod->refptr = alloc_percpu(struct module_ref);
@@ -2580,7 +2596,6 @@ static noinline struct module *load_module(void __user *umod, 
 free_init:

#endif

	module_free(mod, mod->module_init);

 free_core:

	module_free(mod, mod->module_core);

	/* mod will be freed with core. Don't access it beyond this line! */

 free_percpu: