From: Christoph Hellwig <hch@lst.de>
To: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>, Kees Cook <keescook@chromium.org>,
Iurii Zaikin <yzaikin@google.com>,
Luis Chamberlain <mcgrof@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org, netdev@vger.kernel.org,
bpf@vger.kernel.org
Subject: Re: [PATCH 6/6] sysctl: pass kernel pointers to ->proc_handler
Date: Tue, 21 Apr 2020 09:42:41 +0200 [thread overview]
Message-ID: <20200421074241.GB15772@lst.de> (raw)
In-Reply-To: <20200417181718.GN5820@bombadil.infradead.org>
On Fri, Apr 17, 2020 at 11:17:18AM -0700, Matthew Wilcox wrote:
> > if (error)
> > - goto out;
> > + goto out_free_buf;
> >
> > /* careful: calling conventions are nasty here */
>
> I think this comment can go now ;-)
It actually long predates the set_fs that was only added for BPF,
and goes back to:
330d57fb98a91 ("[PATCH] Fix sysctl unregistration oops (CVE-2005-2709)")
in the history.git tree.
> > - } else {
> > - error = table->proc_handler(table, write, buf, &count, ppos);
> > - }
> > + error = table->proc_handler(table, write, kbuf, &count, ppos);
> > + if (error)
> > + goto out_free_buf;
> > +
> > + error = -EFAULT;
> > + if (copy_to_user(ubuf, kbuf, count))
> > + goto out_free_buf;
>
> Can we skip this if !write? Indeed, don't we have to in case the user has
> passed a pointer to a read-only memory page?
Indeed.
next prev parent reply other threads:[~2020-04-21 7:42 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-17 6:41 pass kernel pointers to the sysctl ->proc_handler method Christoph Hellwig
2020-04-17 6:41 ` [PATCH 1/6] bpf-cgroup: remove unused exports Christoph Hellwig
2020-04-17 6:41 ` [PATCH 2/6] firmware_loader: " Christoph Hellwig
2020-04-17 7:43 ` Greg Kroah-Hartman
2020-04-17 7:48 ` Christoph Hellwig
2020-04-17 6:41 ` [PATCH 3/6] mm: remove watermark_boost_factor_sysctl_handler Christoph Hellwig
2020-04-17 6:41 ` [PATCH 4/6] sysctl: remove all extern declaration from sysctl.c Christoph Hellwig
2020-04-22 12:33 ` Eric W. Biederman
2020-04-22 17:26 ` Christoph Hellwig
2020-04-17 6:41 ` [PATCH 5/6] sysctl: avoid forward declarations Christoph Hellwig
2020-04-17 6:41 ` [PATCH 6/6] sysctl: pass kernel pointers to ->proc_handler Christoph Hellwig
2020-04-17 7:45 ` Greg Kroah-Hartman
2020-04-17 18:17 ` Matthew Wilcox
2020-04-21 7:42 ` Christoph Hellwig [this message]
2020-04-17 19:39 ` Andrey Ignatov
2020-04-17 19:50 ` Matthew Wilcox
2020-04-17 22:38 ` Andrey Ignatov
2020-04-21 7:55 ` Christoph Hellwig
2020-04-17 22:36 ` [Potential Spoof] " Andrey Ignatov
2020-04-17 18:00 ` pass kernel pointers to the sysctl ->proc_handler method Luis Chamberlain
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