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 2fc25810509e..7dadc71ce516 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;
 }