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authorDavid Teigland <teigland@redhat.com>2009-03-04 11:17:23 -0600
committerDavid Teigland <teigland@redhat.com>2009-03-11 12:23:59 -0500
commit1fecb1c4b62881e3689ba2dcf93072ae301b597c (patch)
treebd0a111ea40bfaa0697e7b0c341660cd970a23a3 /fs/dlm/user.c
parenta536e38125fe5da8ed49690f30c30a8f651cf1f5 (diff)
dlm: fix length calculation in compat code
Using offsetof() to calculate name length does not work because it does not produce consistent results with with structure packing. This caused memcpy to corrupt memory by copying 4 extra bytes off the end of the buffer on 64 bit kernels with 32 bit userspace (the only case where this 32/64 compat code is used). The fix is to calculate name length directly from the start instead of trying to derive it later using count and offsetof. Signed-off-by: David Teigland <teigland@redhat.com>
Diffstat (limited to 'fs/dlm/user.c')
-rw-r--r--fs/dlm/user.c24
1 files changed, 15 insertions, 9 deletions
diff --git a/fs/dlm/user.c b/fs/dlm/user.c
index 065149e84f4..ebce994ab0b 100644
--- a/fs/dlm/user.c
+++ b/fs/dlm/user.c
@@ -1,5 +1,5 @@
/*
- * Copyright (C) 2006-2008 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2006-2009 Red Hat, Inc. All rights reserved.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
@@ -84,7 +84,7 @@ struct dlm_lock_result32 {
static void compat_input(struct dlm_write_request *kb,
struct dlm_write_request32 *kb32,
- size_t count)
+ int namelen)
{
kb->version[0] = kb32->version[0];
kb->version[1] = kb32->version[1];
@@ -96,8 +96,7 @@ 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;
- memcpy(kb->i.lspace.name, kb32->i.lspace.name, count -
- offsetof(struct dlm_write_request32, i.lspace.name));
+ memcpy(kb->i.lspace.name, kb32->i.lspace.name, namelen);
} else if (kb->cmd == DLM_USER_PURGE) {
kb->i.purge.nodeid = kb32->i.purge.nodeid;
kb->i.purge.pid = kb32->i.purge.pid;
@@ -115,8 +114,7 @@ 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);
- memcpy(kb->i.lock.name, kb32->i.lock.name, count -
- offsetof(struct dlm_write_request32, i.lock.name));
+ memcpy(kb->i.lock.name, kb32->i.lock.name, namelen);
}
}
@@ -539,9 +537,16 @@ static ssize_t device_write(struct file *file, const char __user *buf,
#ifdef CONFIG_COMPAT
if (!kbuf->is64bit) {
struct dlm_write_request32 *k32buf;
+ int namelen = 0;
+
+ if (count > sizeof(struct dlm_write_request32))
+ namelen = count - sizeof(struct dlm_write_request32);
+
k32buf = (struct dlm_write_request32 *)kbuf;
- kbuf = kmalloc(count + 1 + (sizeof(struct dlm_write_request) -
- sizeof(struct dlm_write_request32)), GFP_KERNEL);
+
+ /* add 1 after namelen so that the name string is terminated */
+ kbuf = kzalloc(sizeof(struct dlm_write_request) + namelen + 1,
+ GFP_KERNEL);
if (!kbuf) {
kfree(k32buf);
return -ENOMEM;
@@ -549,7 +554,8 @@ static ssize_t device_write(struct file *file, const char __user *buf,
if (proc)
set_bit(DLM_PROC_FLAGS_COMPAT, &proc->flags);
- compat_input(kbuf, k32buf, count + 1);
+
+ compat_input(kbuf, k32buf, namelen);
kfree(k32buf);
}
#endif