Commit 88173507 authored by Christoph Lameter's avatar Christoph Lameter Committed by Linus Torvalds
Browse files

Modules: handle symbols that have a zero value 



The module subsystem cannot handle symbols that are zero.  If symbols are
present that have a zero value then the module resolver prints out a
message that these symbols are unresolved.

[akinobu.mita@gmail.com: fix __find_symbl() error checks]
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Kay Sievers <kay.sievers@vrfy.org
Signed-off-by: default avatarChristoph Lameter <clameter@sgi.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 596f5601

kernel/module.c

+14 −9
Original line number Diff line number Diff line
@@ -290,7 +290,7 @@ static unsigned long __find_symbol(const char *name, 
		}

	}

	DEBUGP("Failed to find symbol %s\n", name);

	return 0;

	return -ENOENT;

}



/* Search for module by name: must hold module_mutex. */
@@ -783,7 +783,7 @@ void __symbol_put(const char *symbol) 
	const unsigned long *crc;



	preempt_disable();

	if (!__find_symbol(symbol, &owner, &crc, 1))

	if (IS_ERR_VALUE(__find_symbol(symbol, &owner, &crc, 1)))

		BUG();

	module_put(owner);

	preempt_enable();
@@ -929,7 +929,8 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs, 
	const unsigned long *crc;

	struct module *owner;



	if (!__find_symbol("struct_module", &owner, &crc, 1))

	if (IS_ERR_VALUE(__find_symbol("struct_module",

						&owner, &crc, 1)))

		BUG();

	return check_version(sechdrs, versindex, "struct_module", mod,

			     crc);
@@ -978,12 +979,12 @@ static unsigned long resolve_symbol(Elf_Shdr *sechdrs, 


	ret = __find_symbol(name, &owner, &crc,

			!(mod->taints & TAINT_PROPRIETARY_MODULE));

	if (ret) {

	if (!IS_ERR_VALUE(ret)) {

		/* use_module can fail due to OOM,

		   or module initialization or unloading */

		if (!check_version(sechdrs, versindex, name, mod, crc) ||

		    !use_module(mod, owner))

			ret = 0;

			ret = -EINVAL;

	}

	return ret;

}
@@ -1371,7 +1372,9 @@ void *__symbol_get(const char *symbol) 


	preempt_disable();

	value = __find_symbol(symbol, &owner, &crc, 1);

	if (value && strong_try_module_get(owner) != 0)

	if (IS_ERR_VALUE(value))

		value = 0;

	else if (strong_try_module_get(owner))

		value = 0;

	preempt_enable();
@@ -1391,14 +1394,16 @@ static int verify_export_symbols(struct module *mod) 
	const unsigned long *crc;



	for (i = 0; i < mod->num_syms; i++)

		if (__find_symbol(mod->syms[i].name, &owner, &crc, 1)) {

		if (!IS_ERR_VALUE(__find_symbol(mod->syms[i].name,

							&owner, &crc, 1))) {

			name = mod->syms[i].name;

			ret = -ENOEXEC;

			goto dup;

		}



	for (i = 0; i < mod->num_gpl_syms; i++)

		if (__find_symbol(mod->gpl_syms[i].name, &owner, &crc, 1)) {

		if (!IS_ERR_VALUE(__find_symbol(mod->gpl_syms[i].name,

							&owner, &crc, 1))) {

			name = mod->gpl_syms[i].name;

			ret = -ENOEXEC;

			goto dup;
@@ -1448,7 +1453,7 @@ static int simplify_symbols(Elf_Shdr *sechdrs, 
					   strtab + sym[i].st_name, mod);



			/* Ok if resolved.  */

			if (sym[i].st_value != 0)

			if (!IS_ERR_VALUE(sym[i].st_value))

				break;

			/* Ok if weak.  */

			if (ELF_ST_BIND(sym[i].st_info) == STB_WEAK)

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