From: Linus Torvalds <torvalds@linux-foundation.org>
To: gor@linux.ibm.com
Cc: Andrew Morton <akpm@linux-foundation.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Heiko Carstens <heiko.carstens@de.ibm.com>
Subject: Re: [PATCH] procfs: fix mmap() for /proc/vmcore
Date: Fri, 18 May 2018 20:33:37 -0700 [thread overview]
Message-ID: <CA+55aFwxEiiAC+dMMVqQ4igqb7rmn23Bq=BM8fqU=MFRWF1JSw@mail.gmail.com> (raw)
In-Reply-To: <CA+55aFxJb9P2TMCc2Pao-uXcVACK-CTBHmzObAQu=rvs87itvw@mail.gmail.com>
On Fri, May 18, 2018 at 8:20 PM Linus Torvalds <
torvalds@linux-foundation.org> wrote:
> I'd *much* rather just set FMODE_UNSIGNED_OFFSET for /proc/vmcore _only_,
> rather than open up all proc files to issues with 4G+ offsets.
Hmm. I was going to point to the s_maxbytes check in rw_verify_area() and
ask you how that ever worked for that file, but it's not there, the
s_maxbyte checks are only in lseek and in do_splice().
So apparently we protect against llseek + read/write, but we don't protect
against pread64/pwrite64 having offset overflows..
That's crazy. That makes all the s_maxbytes protection much less effective
than it should be. Filesystems that don't get the 64-bit case right will
screw up pread64 and friends.
Al, I'm missing something. Did we always have this gaping hole where we
didn't actually check s_maxbytes against read/write, only
generic_file_llseek? Apparently.
Linus
next prev parent reply other threads:[~2018-05-19 3:33 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-19 3:15 [v4.17-rc5][bisected] be83bbf80682 breaks /proc/vmcore mmap Vasily Gorbik
2018-05-19 3:15 ` [PATCH] procfs: fix mmap() for /proc/vmcore Vasily Gorbik
2018-05-19 3:20 ` Linus Torvalds
2018-05-19 3:33 ` Linus Torvalds [this message]
2018-05-19 3:43 ` Al Viro
2018-05-19 4:12 ` Linus Torvalds
2018-05-19 4:16 ` Linus Torvalds
2018-05-19 11:39 ` Vasily Gorbik
2018-05-19 16:45 ` Linus Torvalds
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