module: make module_address_lookup safe

module_address_lookup releases preemption then returns a pointer into
the module space.  The only user (kallsyms) copies the result, so just
do that under the preempt disable.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 4 insertions, 7 deletions

diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 2fc25810509..7dadc71ce51 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -233,10 +233,11 @@ static unsigned long get_symbol_pos(unsigned long addr,
 int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
 				unsigned long *offset)
 {
+	char namebuf[KSYM_NAME_LEN];
 	if (is_ksym_addr(addr))
 		return !!get_symbol_pos(addr, symbolsize, offset);
 
-	return !!module_address_lookup(addr, symbolsize, offset, NULL);
+	return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf);
 }
 
 /*
@@ -251,8 +252,6 @@ const char *kallsyms_lookup(unsigned long addr,
 			    unsigned long *offset,
 			    char **modname, char *namebuf)
 {
-	const char *msym;
-
 	namebuf[KSYM_NAME_LEN - 1] = 0;
 	namebuf[0] = 0;
 
@@ -268,10 +267,8 @@ const char *kallsyms_lookup(unsigned long addr,
 	}
 
 	/* see if it's in a module */
-	msym = module_address_lookup(addr, symbolsize, offset, modname);
-	if (msym)
-		return strncpy(namebuf, msym, KSYM_NAME_LEN - 1);
-
+	return module_address_lookup(addr, symbolsize, offset, modname,
+				     namebuf);
 	return NULL;
 }