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authorRusty Russell <rusty@rustcorp.com.au>2009-03-31 13:05:29 -0600
committerRusty Russell <rusty@rustcorp.com.au>2009-03-31 13:05:30 +1030
commite180a6b7759a99a28cbcce3547c4c80822cb6c2a (patch)
treed52b950935f3192d13bdd4ad9377b39bab21325e /kernel/params.c
parent15f7176eb1cccec0a332541285ee752b935c1c85 (diff)
param: fix charp parameters set via sysfs
Impact: fix crash on reading from /sys/module/.../ieee80211_default_rc_algo The module_param type "charp" simply sets a char * pointer in the module to the parameter in the commandline string: this is why we keep the (mangled) module command line around. But when set via sysfs (as about 11 charp parameters can be) this memory is freed on the way out of the write(). Future reads hit random mem. So we kstrdup instead: we have to check we're not in early commandline parsing, and we have to note when we've used it so we can reliably kfree the parameter when it's next overwritten, and also on module unload. (Thanks to Randy Dunlap for CONFIG_SYSFS=n fixes) Reported-by: Sitsofe Wheeler <sitsofe@yahoo.com> Diagnosed-by: Frederic Weisbecker <fweisbec@gmail.com> Tested-by: Frederic Weisbecker <fweisbec@gmail.com> Tested-by: Christof Schmitt <christof.schmitt@de.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'kernel/params.c')
-rw-r--r--kernel/params.c26
1 files changed, 25 insertions, 1 deletions
diff --git a/kernel/params.c b/kernel/params.c
index a1e3025b19a..de273ec85bd 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -24,6 +24,9 @@
#include <linux/err.h>
#include <linux/slab.h>
+/* We abuse the high bits of "perm" to record whether we kmalloc'ed. */
+#define KPARAM_KMALLOCED 0x80000000
+
#if 0
#define DEBUGP printk
#else
@@ -217,7 +220,19 @@ int param_set_charp(const char *val, struct kernel_param *kp)
return -ENOSPC;
}
- *(char **)kp->arg = (char *)val;
+ if (kp->perm & KPARAM_KMALLOCED)
+ kfree(*(char **)kp->arg);
+
+ /* This is a hack. We can't need to strdup in early boot, and we
+ * don't need to; this mangled commandline is preserved. */
+ if (slab_is_available()) {
+ kp->perm |= KPARAM_KMALLOCED;
+ *(char **)kp->arg = kstrdup(val, GFP_KERNEL);
+ if (!kp->arg)
+ return -ENOMEM;
+ } else
+ *(const char **)kp->arg = val;
+
return 0;
}
@@ -571,6 +586,15 @@ void module_param_sysfs_remove(struct module *mod)
}
#endif
+void destroy_params(const struct kernel_param *params, unsigned num)
+{
+ unsigned int i;
+
+ for (i = 0; i < num; i++)
+ if (params[i].perm & KPARAM_KMALLOCED)
+ kfree(*(char **)params[i].arg);
+}
+
static void __init kernel_add_sysfs_param(const char *name,
struct kernel_param *kparam,
unsigned int name_skip)