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/dev/mem: dont allow seek to last page

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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>
This commit is contained in:
Wu Fengguang 2010-03-10 15:21:51 -08:00 committed by Linus Torvalds
parent 2cb9a75d13
commit dcefafb6ac
1 changed files with 13 additions and 6 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

19
drivers/char/mem.c
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@ -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); mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
switch (orig) { 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; file->f_pos = offset;
ret = file->f_pos; ret = file->f_pos;
force_successful_syscall_return(); force_successful_syscall_return();
break; break;
case 1:
file->f_pos += offset;
ret = file->f_pos;
force_successful_syscall_return();
break;
default: default:
ret = -EINVAL; ret = -EINVAL;
} }