From: Linus Torvalds <torvalds@linux-foundation.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: James Bottomley <James.Bottomley@hansenpartnership.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
linux-scsi <linux-scsi@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Doug Gilbert <dgilbert@interlog.com>
Subject: Re: [PATCH] scsi: sg: fix v3 compat read/write interface
Date: Wed, 4 Dec 2019 10:32:56 -0800 [thread overview]
Message-ID: <CAHk-=wjBbi2xJZw+7Wqtt3W_mOUSPU2N4w-OES9WUUyXt-DnCg@mail.gmail.com> (raw)
In-Reply-To: <20191204140812.2761761-1-arnd@arndb.de>
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
next prev parent reply other threads:[~2019-12-04 18:33 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-30 18:10 [GIT PULL] first round of SCSI updates for the 5.4+ merge window James Bottomley
2019-12-02 21:57 ` Linus Torvalds
2019-12-02 22:40 ` James Bottomley
2019-12-04 14:05 ` Arnd Bergmann
2019-12-04 14:08 ` [PATCH] scsi: sg: fix v3 compat read/write interface Arnd Bergmann
2019-12-04 18:32 ` Linus Torvalds [this message]
2019-12-04 20:35 ` Arnd Bergmann
2019-12-02 22:00 ` [GIT PULL] first round of SCSI updates for the 5.4+ merge window pr-tracker-bot
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