[PATCH] fix Module taint flags listing in Oops/panic

Module taint flags listing in Oops/panic has a couple of issues:

* taint_flags() doesn't null-terminate the buffer after printing the flags

* per-module taints are only set if the kernel is not already tainted
  (with that particular flag) => only the first offending module gets its
  taint info correctly updated

Some additional changes:

* 'license_gplok' is no longer needed - equivalent to !(taints &
  TAINT_PROPRIETARY_MODULE) - so we can drop it from struct module *
  exporting module taint info via /proc/module:

pwc 88576 0 - Live 0xf8c32000
evilmod 6784 1 pwc, Live 0xf8bbf000 (PF)

Signed-off-by: Florin Malita <fmalita@gmail.com>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 49 insertions, 45 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 7f60e782de1e..67009bd56c52 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -87,6 +87,12 @@ static inline int strong_try_module_get(struct module *mod)
         return try_module_get(mod);
 }
 
+static inline void add_taint_module(struct module *mod, unsigned flag)
+{
+        add_taint(flag);
+        mod->taints |= flag;
+}
+
 /* A thread that wants to hold a reference to a module only while it
  * is running can call ths to safely exit.
  * nfsd and lockd use this.
@@ -847,12 +853,10 @@ static int check_version(Elf_Shdr *sechdrs,
                 return 0;
         }
         /* Not in module's version table.  OK, but that taints the kernel. */
-        if (!(tainted & TAINT_FORCED_MODULE)) {
+        if (!(tainted & TAINT_FORCED_MODULE))
                 printk("%s: no version for \"%s\" found: kernel tainted.\n",
                        mod->name, symname);
-                add_taint(TAINT_FORCED_MODULE);
-                mod->taints |= TAINT_FORCED_MODULE;
-        }
+        add_taint_module(mod, TAINT_FORCED_MODULE);
         return 1;
 }
 
@@ -910,7 +914,8 @@ static unsigned long resolve_symbol(Elf_Shdr *sechdrs,
         unsigned long ret;
         const unsigned long *crc;
 
-        ret = __find_symbol(name, &owner, &crc, mod->license_gplok);
+        ret = __find_symbol(name, &owner, &crc,
+                        !(mod->taints & TAINT_PROPRIETARY_MODULE));
         if (ret) {
                 /* use_module can fail due to OOM, or module unloading */
                 if (!check_version(sechdrs, versindex, name, mod, crc) ||
@@ -1335,12 +1340,11 @@ static void set_license(struct module *mod, const char *license)
         if (!license)
                 license = "unspecified";
 
-        mod->license_gplok = license_is_gpl_compatible(license);
-        if (!mod->license_gplok && !(tainted & TAINT_PROPRIETARY_MODULE)) {
-                printk(KERN_WARNING "%s: module license '%s' taints kernel.\n",
-                       mod->name, license);
-                add_taint(TAINT_PROPRIETARY_MODULE);
-                mod->taints |= TAINT_PROPRIETARY_MODULE;
+        if (!license_is_gpl_compatible(license)) {
+                if (!(tainted & TAINT_PROPRIETARY_MODULE))
+                        printk(KERN_WARNING "%s: module license '%s' taints"
+                                "kernel.\n", mod->name, license);
+                add_taint_module(mod, TAINT_PROPRIETARY_MODULE);
         }
 }
 
@@ -1619,8 +1623,7 @@ static struct module *load_module(void __user *umod,
         modmagic = get_modinfo(sechdrs, infoindex, "vermagic");
         /* This is allowed: modprobe --force will invalidate it. */
         if (!modmagic) {
-                add_taint(TAINT_FORCED_MODULE);
-                mod->taints |= TAINT_FORCED_MODULE;
+                add_taint_module(mod, TAINT_FORCED_MODULE);
                 printk(KERN_WARNING "%s: no version magic, tainting kernel.\n",
                        mod->name);
         } else if (!same_magic(modmagic, vermagic)) {
@@ -1714,14 +1717,10 @@ static struct module *load_module(void __user *umod,
         /* Set up license info based on the info section */
         set_license(mod, get_modinfo(sechdrs, infoindex, "license"));
 
-        if (strcmp(mod->name, "ndiswrapper") == 0) {
-                add_taint(TAINT_PROPRIETARY_MODULE);
-                mod->taints |= TAINT_PROPRIETARY_MODULE;
-        }
-        if (strcmp(mod->name, "driverloader") == 0) {
-                add_taint(TAINT_PROPRIETARY_MODULE);
-                mod->taints |= TAINT_PROPRIETARY_MODULE;
-        }
+        if (strcmp(mod->name, "ndiswrapper") == 0)
+                add_taint_module(mod, TAINT_PROPRIETARY_MODULE);
+        if (strcmp(mod->name, "driverloader") == 0)
+                add_taint_module(mod, TAINT_PROPRIETARY_MODULE);
 
         /* Set up MODINFO_ATTR fields */
         setup_modinfo(mod, sechdrs, infoindex);
@@ -1766,8 +1765,7 @@ static struct module *load_module(void __user *umod,
             (mod->num_unused_gpl_syms && !unusedgplcrcindex)) {
                 printk(KERN_WARNING "%s: No versions for exported symbols."
                        " Tainting kernel.\n", mod->name);
-                add_taint(TAINT_FORCED_MODULE);
-                mod->taints |= TAINT_FORCED_MODULE;
+                add_taint_module(mod, TAINT_FORCED_MODULE);
         }
 #endif
 
@@ -2132,9 +2130,33 @@ static void m_stop(struct seq_file *m, void *p)
         mutex_unlock(&module_mutex);
 }
 
+static char *taint_flags(unsigned int taints, char *buf)
+{
+        int bx = 0;
+
+        if (taints) {
+                buf[bx++] = '(';
+                if (taints & TAINT_PROPRIETARY_MODULE)
+                        buf[bx++] = 'P';
+                if (taints & TAINT_FORCED_MODULE)
+                        buf[bx++] = 'F';
+                /*
+                 * TAINT_FORCED_RMMOD: could be added.
+                 * TAINT_UNSAFE_SMP, TAINT_MACHINE_CHECK, TAINT_BAD_PAGE don't
+                 * apply to modules.
+                 */
+                buf[bx++] = ')';
+        }
+        buf[bx] = '\0';
+
+        return buf;
+}
+
 static int m_show(struct seq_file *m, void *p)
 {
         struct module *mod = list_entry(p, struct module, list);
+        char buf[8];
+
         seq_printf(m, "%s %lu",
                    mod->name, mod->init_size + mod->core_size);
         print_unload_info(m, mod);
@@ -2147,6 +2169,10 @@ static int m_show(struct seq_file *m, void *p)
         /* Used by oprofile and other similar tools. */
         seq_printf(m, " 0x%p", mod->module_core);
 
+        /* Taints info */
+        if (mod->taints)
+                seq_printf(m, " %s", taint_flags(mod->taints, buf));
+
         seq_printf(m, "\n");
         return 0;
 }
@@ -2235,28 +2261,6 @@ struct module *module_text_address(unsigned long addr)
         return mod;
 }
 
-static char *taint_flags(unsigned int taints, char *buf)
-{
-        *buf = '\0';
-        if (taints) {
-                int bx;
-
-                buf[0] = '(';
-                bx = 1;
-                if (taints & TAINT_PROPRIETARY_MODULE)
-                        buf[bx++] = 'P';
-                if (taints & TAINT_FORCED_MODULE)
-                        buf[bx++] = 'F';
-                /*
-                 * TAINT_FORCED_RMMOD: could be added.
-                 * TAINT_UNSAFE_SMP, TAINT_MACHINE_CHECK, TAINT_BAD_PAGE don't
-                 * apply to modules.
-                 */
-                buf[bx] = ')';
-        }
-        return buf;
-}
-
 /* Don't grab lock, we're oopsing. */
 void print_modules(void)
 {