Commit 9a1bd63c authored by Miroslav Benes's avatar Miroslav Benes Committed by Jiri Kosina
Browse files

livepatch: add module locking around kallsyms calls 



The list of loaded modules is walked through in
module_kallsyms_on_each_symbol (called by kallsyms_on_each_symbol). The
module_mutex lock should be acquired to prevent potential corruptions
in the list.

This was uncovered with new lockdep asserts in module code introduced by
the commit 0be964be ("module: Sanitize RCU usage and locking") in
recent next- trees.

Signed-off-by: default avatarMiroslav Benes <mbenes@suse.cz>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 9497d738

kernel/livepatch/core.c

+13 −5
Original line number Original line Diff line number Diff line
@@ -179,7 +179,9 @@ static int klp_find_object_symbol(const char *objname, const char *name, 
		.count = 0

		.count = 0

	};

	};





	mutex_lock(&module_mutex);

	kallsyms_on_each_symbol(klp_find_callback, &args);

	kallsyms_on_each_symbol(klp_find_callback, &args);

	mutex_unlock(&module_mutex);





	if (args.count == 0)

	if (args.count == 0)

		pr_err("symbol '%s' not found in symbol table\n", name);

		pr_err("symbol '%s' not found in symbol table\n", name);
@@ -219,15 +221,21 @@ static int klp_verify_vmlinux_symbol(const char *name, unsigned long addr) 
		.name = name,

		.name = name,

		.addr = addr,

		.addr = addr,

	};

	};

	int ret;





	if (kallsyms_on_each_symbol(klp_verify_callback, &args))

	mutex_lock(&module_mutex);

		return 0;

	ret = kallsyms_on_each_symbol(klp_verify_callback, &args);

	mutex_unlock(&module_mutex);





	if (!ret) {

		pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n",

		pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n",

			name, addr);

			name, addr);

		return -EINVAL;

		return -EINVAL;

	}

	}





	return 0;

}



static int klp_find_verify_func_addr(struct klp_object *obj,

static int klp_find_verify_func_addr(struct klp_object *obj,

				     struct klp_func *func)

				     struct klp_func *func)

{

{

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