dlm: dlm/user.c input validation fixes

a) in device_write(): add sentinel NUL byte, making sure that lspace.name will
be NUL-terminated
b) in compat_input() be keep it simple about the amounts of data we are copying.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Teigland <teigland@redhat.com>

1 files changed, 8 insertions, 11 deletions

diff --git a/fs/dlm/user.c b/fs/dlm/user.c
index 7cbc6826239b..c3060458b68e 100644
--- a/fs/dlm/user.c
+++ b/fs/dlm/user.c
@@ -82,7 +82,7 @@ struct dlm_lock_result32 {
 
 static void compat_input(struct dlm_write_request *kb,
                          struct dlm_write_request32 *kb32,
-                         int max_namelen)
+                         size_t count)
 {
         kb->version[0] = kb32->version[0];
         kb->version[1] = kb32->version[1];
@@ -94,7 +94,8 @@ static void compat_input(struct dlm_write_request *kb,
             kb->cmd == DLM_USER_REMOVE_LOCKSPACE) {
                 kb->i.lspace.flags = kb32->i.lspace.flags;
                 kb->i.lspace.minor = kb32->i.lspace.minor;
-                strcpy(kb->i.lspace.name, kb32->i.lspace.name);
+                memcpy(kb->i.lspace.name, kb32->i.lspace.name, count -
+                        offsetof(struct dlm_write_request32, i.lspace.name));
         } else if (kb->cmd == DLM_USER_PURGE) {
                 kb->i.purge.nodeid = kb32->i.purge.nodeid;
                 kb->i.purge.pid = kb32->i.purge.pid;
@@ -112,11 +113,8 @@ static void compat_input(struct dlm_write_request *kb,
                 kb->i.lock.bastaddr = (void *)(long)kb32->i.lock.bastaddr;
                 kb->i.lock.lksb = (void *)(long)kb32->i.lock.lksb;
                 memcpy(kb->i.lock.lvb, kb32->i.lock.lvb, DLM_USER_LVB_LEN);
-                if (kb->i.lock.namelen <= max_namelen)
-                        memcpy(kb->i.lock.name, kb32->i.lock.name,
-                               kb->i.lock.namelen);
-                else
-                        kb->i.lock.namelen = max_namelen;
+                memcpy(kb->i.lock.name, kb32->i.lock.name, count -
+                        offsetof(struct dlm_write_request32, i.lock.name));
         }
 }
 
@@ -508,7 +506,7 @@ static ssize_t device_write(struct file *file, const char __user *buf,
 #endif
                 return -EINVAL;
 
-        kbuf = kmalloc(count, GFP_KERNEL);
+        kbuf = kzalloc(count + 1, GFP_KERNEL);
         if (!kbuf)
                 return -ENOMEM;
 
@@ -526,15 +524,14 @@ static ssize_t device_write(struct file *file, const char __user *buf,
         if (!kbuf->is64bit) {
                 struct dlm_write_request32 *k32buf;
                 k32buf = (struct dlm_write_request32 *)kbuf;
-                kbuf = kmalloc(count + (sizeof(struct dlm_write_request) -
+                kbuf = kmalloc(count + 1 + (sizeof(struct dlm_write_request) -
                                sizeof(struct dlm_write_request32)), GFP_KERNEL);
                 if (!kbuf)
                         return -ENOMEM;
 
                 if (proc)
                         set_bit(DLM_PROC_FLAGS_COMPAT, &proc->flags);
-                compat_input(kbuf, k32buf,
-                             count - sizeof(struct dlm_write_request32));
+                compat_input(kbuf, k32buf, count + 1);
                 kfree(k32buf);
         }
 #endif