/dev/mem: dont allow seek to last page (dcefafb6) · Commits · e / devices / android_kernel_teracube_emerald

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>

drivers/char/mem.c

+13 −6

Original line number	Diff line number	Diff line
		@@ -708,13 +708,20 @@ 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:
		file->f_pos = offset;
		ret = file->f_pos;
		force_successful_syscall_return();
		case SEEK_CUR:
		offset += file->f_pos;
		if ((unsigned long long)offset <
		(unsigned long long)file->f_pos) {
		ret = -EOVERFLOW;
		break;
		case 1:
		file->f_pos += offset;
		}
		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;