ecryptfs: Bugfix for error related to ecryptfs_hash_buckets

The function ecryptfs_uid_hash wrongly assumes that the
second parameter to hash_long() is the number of hash
buckets instead of the number of hash bits.
This patch fixes that and renames the variable
ecryptfs_hash_buckets to ecryptfs_hash_bits to make it
clearer.

Fixes: CVE-2010-2492

Signed-off-by: Andre Osterhues <aosterhues@escrypt.com>
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 8 deletions

diff --git a/fs/ecryptfs/messaging.c b/fs/ecryptfs/messaging.c
index 2d8dbce9d485..46c4dd8dfcc3 100644
--- a/fs/ecryptfs/messaging.c
+++ b/fs/ecryptfs/messaging.c
@@ -31,9 +31,9 @@ static struct mutex ecryptfs_msg_ctx_lists_mux;
 
 static struct hlist_head *ecryptfs_daemon_hash;
 struct mutex ecryptfs_daemon_hash_mux;
-static int ecryptfs_hash_buckets;
+static int ecryptfs_hash_bits;
 #define ecryptfs_uid_hash(uid) \
-        hash_long((unsigned long)uid, ecryptfs_hash_buckets)
+        hash_long((unsigned long)uid, ecryptfs_hash_bits)
 
 static u32 ecryptfs_msg_counter;
 static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;
@@ -486,18 +486,19 @@ int ecryptfs_init_messaging(void)
         }
         mutex_init(&ecryptfs_daemon_hash_mux);
         mutex_lock(&ecryptfs_daemon_hash_mux);
-        ecryptfs_hash_buckets = 1;
-        while (ecryptfs_number_of_users >> ecryptfs_hash_buckets)
-                ecryptfs_hash_buckets++;
+        ecryptfs_hash_bits = 1;
+        while (ecryptfs_number_of_users >> ecryptfs_hash_bits)
+                ecryptfs_hash_bits++;
         ecryptfs_daemon_hash = kmalloc((sizeof(struct hlist_head)
-                                        * ecryptfs_hash_buckets), GFP_KERNEL);
+                                        * (1 << ecryptfs_hash_bits)),
+                                       GFP_KERNEL);
         if (!ecryptfs_daemon_hash) {
                 rc = -ENOMEM;
                 printk(KERN_ERR "%s: Failed to allocate memory\n", __func__);
                 mutex_unlock(&ecryptfs_daemon_hash_mux);
                 goto out;
         }
-        for (i = 0; i < ecryptfs_hash_buckets; i++)
+        for (i = 0; i < (1 << ecryptfs_hash_bits); i++)
                 INIT_HLIST_HEAD(&ecryptfs_daemon_hash[i]);
         mutex_unlock(&ecryptfs_daemon_hash_mux);
         ecryptfs_msg_ctx_arr = kmalloc((sizeof(struct ecryptfs_msg_ctx)
@@ -554,7 +555,7 @@ void ecryptfs_release_messaging(void)
                 int i;
 
                 mutex_lock(&ecryptfs_daemon_hash_mux);
-                for (i = 0; i < ecryptfs_hash_buckets; i++) {
+                for (i = 0; i < (1 << ecryptfs_hash_bits); i++) {
                         int rc;
 
                         hlist_for_each_entry(daemon, elem,