Possible race condition and consequent crash

[procprotect.git] / procprotect.c

diff --git a/procprotect.c b/procprotect.c
index 1ceea46..950be09 100644 (file)
--- a/procprotect.c
+++ b/procprotect.c
@@ -2,6 +2,7 @@
 #include <linux/moduleparam.h>
 #include <linux/types.h>
 #include <linux/kernel.h>
+#include <linux/version.h>
 #include <linux/fs_struct.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
@@ -33,7 +34,12 @@
 #error "This code does not support your architecture"
 #endif
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,8,0)
 static char *aclpath = "procprotect";
+#else
+static char *aclpath __devinitdata = "procprotect";
+#endif
+
 static struct qstr aclqpath;
 
 module_param(aclpath, charp, 0);
@@ -151,8 +157,12 @@ static int lookup_slow_entry(struct kretprobe_instance *ri, struct pt_regs *regs
 
 static int lookup_slow_ret(struct kretprobe_instance *ri, struct pt_regs *regs)
 {
-    struct procprotect_ctx *ctx = (struct procprotect_ctx *) ri->data;
-    int ret = regs->ax;
+    struct procprotect_ctx *ctx;
+    int ret;
+
+    if (!ri) {/* Race condition?*/ return 0;}
+    ctx = (struct procprotect_ctx *) ri->data;
+    ret = regs->ax;
 
     if (ret==0) {
         /* The kernel is going to honor the request. Here's where we step in */
@@ -283,11 +293,12 @@ int procfile_write(struct file *file, const char *buffer, unsigned long count, v
 
 static int __init procprotect_init(void)
 {
-    printk("Procprotect: starting procprotect version %s with ACLs at path %s.\n",
-            VERSION_STR, aclpath);
     int ret;
     int i;
 
+    printk("Procprotect: starting procprotect version %s with ACLs at path %s.\n",
+            VERSION_STR, aclpath);
+
     for(i=0;i<HASH_SIZE;i++) {
         INIT_HLIST_HEAD(&procprotect_hash[i]);
     }