Fix race between cat /proc/*/wchan and rmmod et al
kallsyms_lookup() can go iterating over modules list unprotected which is OK
for emergency situations (oops), but not OK for regular stuff like
/proc/*/wchan.
Introduce lookup_symbol_name()/lookup_module_symbol_name() which copy symbol
name into caller-supplied buffer or return -ERANGE. All copying is done with
module_mutex held, so...
Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c
index fe9314a..b734ca4 100644
--- a/kernel/time/timer_list.c
+++ b/kernel/time/timer_list.c
@@ -38,15 +38,12 @@
static void print_name_offset(struct seq_file *m, void *sym)
{
- unsigned long addr = (unsigned long)sym;
- char namebuf[KSYM_NAME_LEN+1];
- const char *sym_name;
+ char symname[KSYM_NAME_LEN+1];
- sym_name = kallsyms_lookup(addr, NULL, NULL, NULL, namebuf);
- if (sym_name)
- SEQ_printf(m, "%s", sym_name);
- else
+ if (lookup_symbol_name((unsigned long)sym, symname) < 0)
SEQ_printf(m, "<%p>", sym);
+ else
+ SEQ_printf(m, "%s", symname);
}
static void
