Commit dcefafb6 authored by Wu Fengguang's avatar Wu Fengguang Committed by Linus Torvalds

/dev/mem: dont allow seek to last page

So as to return a uniform error -EOVERFLOW instead of a random one:

# kmem-seek 0xfffffffffffffff0
seek /dev/kmem: Device or resource busy
# kmem-seek 0xfffffffffffffff1
seek /dev/kmem: Block device required

Suggested by OGAWA Hirofumi.

Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: default avatarWu Fengguang <fengguang.wu@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2cb9a75d
......@@ -708,16 +708,23 @@ static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
switch (orig) {
case 0:
case SEEK_CUR:
offset += file->f_pos;
if ((unsigned long long)offset <
(unsigned long long)file->f_pos) {
ret = -EOVERFLOW;
break;
}
case SEEK_SET:
/* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
if ((unsigned long long)offset >= ~0xFFFULL) {
ret = -EOVERFLOW;
break;
}
file->f_pos = offset;
ret = file->f_pos;
force_successful_syscall_return();
break;
case 1:
file->f_pos += offset;
ret = file->f_pos;
force_successful_syscall_return();
break;
default:
ret = -EINVAL;
}
......
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