The first thing drivers/char/mem.c:read_kmem does is convert the
loff_t it gets as the offset for reading into an unsigned int. This
patch makes the kmem driver's llseek operator do that up-front, so
that fs/read_write.c:rw_verify_area doesn't return -EINVAL when
we try to read from higher addresses.
It's ugly but so is the existing code. And it won't fix 64-bit
archs AFAICT. Tested on 2.6.11, patch offsets fixed up for 2.6.13-rc6.
Signed-off-by: Chuck Ebbert <[EMAIL PROTECTED]>
Index: 2.6.13-rc6/drivers/char/mem.c
===================================================================
--- 2.6.13-rc6.orig/drivers/char/mem.c 2005-08-14 11:49:11.000000000 -0400
+++ 2.6.13-rc6/drivers/char/mem.c 2005-08-14 11:51:15.000000000 -0400
@@ -747,6 +747,29 @@
return ret;
}
+static loff_t kmem_lseek(struct file * file, loff_t offset, int orig)
+{
+ loff_t ret = -EINVAL;
+
+ if (orig == 2) /* sys_seek/llseek has checked orig = {012} */
+ goto out;
+
+ down(&file->f_dentry->d_inode->i_sem);
+ switch (orig) {
+ case 0:
+ file->f_pos = offset;
+ break;
+ case 1:
+ file->f_pos += offset;
+ }
+ ret = file->f_pos;
+ file->f_pos = (loff_t)(unsigned long)file->f_pos;
+ force_successful_syscall_return();
+ up(&file->f_dentry->d_inode->i_sem);
+out:
+ return ret;
+}
+
static int open_port(struct inode * inode, struct file * filp)
{
return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
@@ -769,7 +792,7 @@
};
static struct file_operations kmem_fops = {
- .llseek = memory_lseek,
+ .llseek = kmem_lseek,
.read = read_kmem,
.write = write_kmem,
.mmap = mmap_kmem,
__
Chuck
-
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