On Fri 24-06-16 01:30:10, [email protected] wrote: > From: chenjie <[email protected]> > > cat /dev/kmem and echo > /dev/kmem will lead panic
Writing to /dev/kmem without being extremely careful is a disaster AFAIK and even reading from the file can lead to unexpected results. Anyway I am trying to understand what exactly you are trying to fix here. Why writing to/reading from zero pfn should be any special wrt. any other potentially dangerous addresses > > Signed-off-by: chenjie <[email protected]> > --- > drivers/char/mem.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/drivers/char/mem.c b/drivers/char/mem.c > index 71025c2..4bdde28 100644 > --- a/drivers/char/mem.c > +++ b/drivers/char/mem.c > @@ -412,6 +412,8 @@ static ssize_t read_kmem(struct file *file, char __user > *buf, > * by the kernel or data corruption may occur > */ > kbuf = xlate_dev_kmem_ptr((void *)p); > + if (!kbuf) > + return -EFAULT; > > if (copy_to_user(buf, kbuf, sz)) > return -EFAULT; > @@ -482,6 +484,11 @@ static ssize_t do_write_kmem(unsigned long p, const char > __user *buf, > * corruption may occur. > */ > ptr = xlate_dev_kmem_ptr((void *)p); > + if (!ptr) { > + if (written) > + break; > + return -EFAULT; > + } > > copied = copy_from_user(ptr, buf, sz); > if (copied) { > -- > 1.8.0 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to [email protected]. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"[email protected]";> [email protected] </a> -- Michal Hocko SUSE Labs
