[PATCH] powerpc: fix large nvram access

/dev/nvram uses the user-provided read/write size
for kmalloc, which fails, if a large number is passed.
This will always use a single page at most, which
can be expected to succeed.

Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/arch/powerpc/kernel/nvram_64.c b/arch/powerpc/kernel/nvram_64.c
index c0fcd29..fd7db8d 100644 (file)
--- a/arch/powerpc/kernel/nvram_64.c
+++ b/arch/powerpc/kernel/nvram_64.c
@@ -80,80 +80,74 @@ static loff_t dev_nvram_llseek(struct file *file, loff_t offset, int origin)
 static ssize_t dev_nvram_read(struct file *file, char __user *buf,
                          size_t count, loff_t *ppos)
 {
-       ssize_t len;
-       char *tmp_buffer;
-       int size;
+       ssize_t ret;
+       char *tmp = NULL;
+       ssize_t size;
 
-       if (ppc_md.nvram_size == NULL)
-               return -ENODEV;
+       ret = -ENODEV;
+       if (!ppc_md.nvram_size)
+               goto out;
+
+       ret = 0;
        size = ppc_md.nvram_size();
+       if (*ppos >= size || size < 0)
+               goto out;
 
-       if (!access_ok(VERIFY_WRITE, buf, count))
-               return -EFAULT;
-       if (*ppos >= size)
-               return 0;
-       if (count > size) 
-               count = size;
+       count = min_t(size_t, count, size - *ppos);
+       count = min(count, PAGE_SIZE);
 
-       tmp_buffer = (char *) kmalloc(count, GFP_KERNEL);
-       if (!tmp_buffer) {
-               printk(KERN_ERR "dev_read_nvram: kmalloc failed\n");
-               return -ENOMEM;
-       }
+       ret = -ENOMEM;
+       tmp = kmalloc(count, GFP_KERNEL);
+       if (!tmp)
+               goto out;
 
-       len = ppc_md.nvram_read(tmp_buffer, count, ppos);
-       if ((long)len <= 0) {
-               kfree(tmp_buffer);
-               return len;
-       }
+       ret = ppc_md.nvram_read(tmp, count, ppos);
+       if (ret <= 0)
+               goto out;
 
-       if (copy_to_user(buf, tmp_buffer, len)) {
-               kfree(tmp_buffer);
-               return -EFAULT;
-       }
+       if (copy_to_user(buf, tmp, ret))
+               ret = -EFAULT;
 
-       kfree(tmp_buffer);
-       return len;
+out:
+       kfree(tmp);
+       return ret;
 
 }
 
 static ssize_t dev_nvram_write(struct file *file, const char __user *buf,
-                          size_t count, loff_t *ppos)
+                         size_t count, loff_t *ppos)
 {
-       ssize_t len;
-       char * tmp_buffer;
-       int size;
+       ssize_t ret;
+       char *tmp = NULL;
+       ssize_t size;
 
-       if (ppc_md.nvram_size == NULL)
-               return -ENODEV;
+       ret = -ENODEV;
+       if (!ppc_md.nvram_size)
+               goto out;
+
+       ret = 0;
        size = ppc_md.nvram_size();
+       if (*ppos >= size || size < 0)
+               goto out;
 
-       if (!access_ok(VERIFY_READ, buf, count))
-               return -EFAULT;
-       if (*ppos >= size)
-               return 0;
-       if (count > size)
-               count = size;
+       count = min_t(size_t, count, size - *ppos);
+       count = min(count, PAGE_SIZE);
 
-       tmp_buffer = (char *) kmalloc(count, GFP_KERNEL);
-       if (!tmp_buffer) {
-               printk(KERN_ERR "dev_nvram_write: kmalloc failed\n");
-               return -ENOMEM;
-       }
-       
-       if (copy_from_user(tmp_buffer, buf, count)) {
-               kfree(tmp_buffer);
-               return -EFAULT;
-       }
+       ret = -ENOMEM;
+       tmp = kmalloc(count, GFP_KERNEL);
+       if (!tmp)
+               goto out;
 
-       len = ppc_md.nvram_write(tmp_buffer, count, ppos);
-       if ((long)len <= 0) {
-               kfree(tmp_buffer);
-               return len;
-       }
+       ret = -EFAULT;
+       if (copy_from_user(tmp, buf, count))
+               goto out;
+
+       ret = ppc_md.nvram_write(tmp, count, ppos);
+
+out:
+       kfree(tmp);
+       return ret;
 
-       kfree(tmp_buffer);
-       return len;
 }
 
 static int dev_nvram_ioctl(struct inode *inode, struct file *file,