Make the taint flags reliable

It's somewhat unlikely that it happens, but right now a race window
between interrupts or machine checks or oopses could corrupt the tainted
bitmap because it is modified in a non atomic fashion.

Convert the taint variable to an unsigned long and use only atomic bit
operations on it.

Unfortunately this means the intvec sysctl functions cannot be used on it
anymore.

It turned out the taint sysctl handler could actually be simplified a bit
(since it only increases capabilities) so this patch actually removes
code.

[akpm@linux-foundation.org: remove unneeded include]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 9db11911e04b..dd9ac6ad5cb9 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -100,7 +100,7 @@ static inline int strong_try_module_get(struct module *mod)
 static inline void add_taint_module(struct module *mod, unsigned flag)
 {
         add_taint(flag);
-        mod->taints |= flag;
+        mod->taints |= (1U << flag);
 }
 
 /*
@@ -923,7 +923,7 @@ static const char vermagic[] = VERMAGIC_STRING;
 static int try_to_force_load(struct module *mod, const char *symname)
 {
 #ifdef CONFIG_MODULE_FORCE_LOAD
-        if (!(tainted & TAINT_FORCED_MODULE))
+        if (!test_taint(TAINT_FORCED_MODULE))
                 printk("%s: no version for \"%s\" found: kernel tainted.\n",
                        mod->name, symname);
         add_taint_module(mod, TAINT_FORCED_MODULE);
@@ -1033,7 +1033,7 @@ static unsigned long resolve_symbol(Elf_Shdr *sechdrs,
         const unsigned long *crc;
 
         ret = find_symbol(name, &owner, &crc,
-                          !(mod->taints & TAINT_PROPRIETARY_MODULE), true);
+                          !(mod->taints & (1 << TAINT_PROPRIETARY_MODULE)), true);
         if (!IS_ERR_VALUE(ret)) {
                 /* use_module can fail due to OOM,
                    or module initialization or unloading */
@@ -1634,7 +1634,7 @@ static void set_license(struct module *mod, const char *license)
                 license = "unspecified";
 
         if (!license_is_gpl_compatible(license)) {
-                if (!(tainted & TAINT_PROPRIETARY_MODULE))
+                if (!test_taint(TAINT_PROPRIETARY_MODULE))
                         printk(KERN_WARNING "%s: module license '%s' taints "
                                 "kernel.\n", mod->name, license);
                 add_taint_module(mod, TAINT_PROPRIETARY_MODULE);
@@ -2552,9 +2552,9 @@ static char *module_flags(struct module *mod, char *buf)
             mod->state == MODULE_STATE_GOING ||
             mod->state == MODULE_STATE_COMING) {
                 buf[bx++] = '(';
-                if (mod->taints & TAINT_PROPRIETARY_MODULE)
+                if (mod->taints & (1 << TAINT_PROPRIETARY_MODULE))
                         buf[bx++] = 'P';
-                if (mod->taints & TAINT_FORCED_MODULE)
+                if (mod->taints & (1 << TAINT_FORCED_MODULE))
                         buf[bx++] = 'F';
                 /*
                  * TAINT_FORCED_RMMOD: could be added.