From 65afac7d80ab3bc9f81e75eafb71eeb92a3ebdef Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Thu, 29 Oct 2009 08:56:16 -0600 Subject: param: fix lots of bugs with writing charp params from sysfs, by leaking mem. e180a6b7759a "param: fix charp parameters set via sysfs" fixed the case where charp parameters written via sysfs were freed, leaving drivers accessing random memory. Unfortunately, storing a flag in the kparam struct was a bad idea: it's rodata so setting it causes an oops on some archs. But that's not all: 1) module_param_array() on charp doesn't work reliably, since we use an uninitialized temporary struct kernel_param. 2) there's a fundamental race if a module uses this parameter and then it's changed: they will still access the old, freed, memory. The simplest fix (ie. for 2.6.32) is to never free the memory. This prevents all these problems, at cost of a memory leak. In practice, there are only 18 places where a charp is writable via sysfs, and all are root-only writable. Reported-by: Takashi Iwai Cc: Sitsofe Wheeler Cc: Frederic Weisbecker Cc: Christof Schmitt Signed-off-by: Rusty Russell Cc: stable@kernel.org --- include/linux/moduleparam.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include') diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h index 6547c3c..82a9124 100644 --- a/include/linux/moduleparam.h +++ b/include/linux/moduleparam.h @@ -37,7 +37,6 @@ typedef int (*param_set_fn)(const char *val, struct kernel_param *kp); typedef int (*param_get_fn)(char *buffer, struct kernel_param *kp); /* Flag bits for kernel_param.flags */ -#define KPARAM_KMALLOCED 1 #define KPARAM_ISBOOL 2 struct kernel_param { -- cgit v1.1