Messages in this thread | | | From | Linus Torvalds <> | Date | Wed, 4 Dec 2019 10:32:56 -0800 | Subject | Re: [PATCH] scsi: sg: fix v3 compat read/write interface |
| |
On Wed, Dec 4, 2019 at 6:08 AM Arnd Bergmann <arnd@arndb.de> wrote: > > To address both of these, move the definition of compat_sg_io_hdr > into a scsi/sg.h to make it visible to sg.c and rewrite the logic > for reading req_pack_id as well as the size check to a simpler > version that gets the expected results.
I think the patch is a good thing, except for this part:
> @@ -575,6 +561,14 @@ sg_new_read(Sg_fd * sfp, char __user *buf, size_t count, Sg_request * srp) > int err = 0, err2; > int len; > > +#ifdef CONFIG_COMPAT > + if (in_compat_syscall()) { > + if (count < sizeof(struct compat_sg_io_hdr)) { > + err = -EINVAL; > + goto err_out; > + } > + } else > +#endif > if (count < SZ_SG_IO_HDR) { > err = -EINVAL; > goto err_out;
Yes, yes, I know we do things like that in some other places too, but I really detest this kind of ifdeffery.
That
} else #endif if (count < SZ_SG_IO_HDR) {
is just evil. Please don't add things like this where the #ifdef section has subtle semantic continuations outside of it. If somebody adds a statement in between there, it now acts completely wrong.
I think you can remove the #ifdef entirely. If CONFIG_COMPAT isn't set, I think in_compat_syscall() just turns to 0, and the code gets optimized away.
Hmm?
Linus
| |