/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: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 48788db..e3f5577 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -708,16 +708,23 @@
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;
}