On Wed, Jun 05, 2019 at 08:41:11AM +0200, Jiri Slaby wrote: > On 31. 05. 19, 3:27, Gen Zhang wrote: > > In sg_write(), the opcode of the command is fetched the first time from > > the userspace by __get_user(). Then the whole command, the opcode > > included, is fetched again from userspace by __copy_from_user(). > > However, a malicious user can change the opcode between the two fetches. > > This can cause inconsistent data and potential errors as cmnd is used in > > the following codes. > > > > Thus we should check opcode between the two fetches to prevent this. > > > > Signed-off-by: Gen Zhang <blackgod016574@xxxxxxxxx> > > --- > > diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c > > index d3f1531..a2971b8 100644 > > --- a/drivers/scsi/sg.c > > +++ b/drivers/scsi/sg.c > > @@ -694,6 +694,8 @@ sg_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos) > > hp->flags = input_size; /* structure abuse ... */ > > hp->pack_id = old_hdr.pack_id; > > hp->usr_ptr = NULL; > > + if (opcode != cmnd[0]) > > + return -EINVAL; > > if (__copy_from_user(cmnd, buf, cmd_size)) > > return -EFAULT; > > You are sending the same patches like a broken machine. Please STOP this > and give people some time to actually review your patches! (Don't expect > replies in days.) > Thanks for your reply. I resubmitted this one after 8-day-no-reply. I don't judge whether this is a short time period or not. I politely hope that you can reply more kindly. I am just a PhD candidate. All I did is submitting patches, discussing with maintainers in accordance with linux community rules for academic papers. I guess that you might be busy person and hope that submitting patches didn't bother you. Thanks Gen > I already commented on this apparently broken one earlier... > > thanks, > -- > js > suse labs
