[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
--- a/arch/powerpc/kernel/nvram_64.c
+++ b/arch/powerpc/kernel/nvram_64.c
@@ -80,80 +80,74 @@
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;
- kfree(tmp_buffer);
- return len;
+ ret = ppc_md.nvram_write(tmp, count, ppos);
+
+out:
+ kfree(tmp);
+ return ret;
+
}
static int dev_nvram_ioctl(struct inode *inode, struct file *file,
