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@xxxxxxxxxxxxxxxxxx>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
drivers/char/mem.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)
--- linux-mm.orig/drivers/char/mem.c 2010-01-30 17:41:51.000000000 +0800
+++ linux-mm/drivers/char/mem.c 2010-01-30 17:42:29.000000000 +0800
@@ -721,16 +721,23 @@ static loff_t memory_lseek(struct file *
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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