From: mingo@kernel.org (Ingo Molnar)
Subject: [Linux-kselftest-mirror] [PATCH 2/5] selftests/x86: fix vDSO selftest segfault for vsyscall=none
Date: Sun, 11 Feb 2018 19:24:28 +0100 [thread overview]
Message-ID: <20180211182428.e7isprkt6hbuq3dk@gmail.com> (raw)
Message-ID: <20180211182428.BkYETHx7HU4p7Wwb1y3giq2u9gp6L180ECto4NEYgqI@z> (raw)
In-Reply-To: <20180211130029.GA23754@light.dominikbrodowski.net>
* Dominik Brodowski <linux@dominikbrodowski.net> wrote:
> On Sun, Feb 11, 2018@01:17:14PM +0100, Dominik Brodowski wrote:
> > On Sun, Feb 11, 2018@12:21:53PM +0100, Ingo Molnar wrote:
> > >
> > > * Dominik Brodowski <linux@dominikbrodowski.net> wrote:
> > >
> > > > + char name[128];
> > > > + if (sscanf(line, "%p-%p %c-%cp %*x %*x:%*x %*u %s",
> > > > + &start, &end, &r, &x, name) != 5)
> > >
> > > So that's a buffer overflow waiting to happen, if a line in 'maps' gets too large,
> > > right?
> >
> > ... as does tools/testing/selftests/x86/test_vsyscall.c already now, right?
> > Will fix both up with an additional patch.
>
> Maybe no fix is needed after all: The fgets() call a few lines above
> limits "line" to 127 chars max. So "name" can't even get close to 128
> chars, right?
>
> char line[128];
> ...
> while (fgets(line, sizeof(line), maps)) {
Yeah, probably - but still, this connection and the sscanf() guarantee is not
obvious at first sight, so please improve this to derive from the same value
(define a LINE_MAX size or such), plus maybe add a comment to the sscanf() line
that this is safe because strlen(name) >= strlen(line).
Thanks,
Ingo
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next prev parent reply other threads:[~2018-02-11 18:24 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-11 11:10 [Linux-kselftest-mirror] [PATCH 0/5] selftests/x86: fixes for !CONFIG_IA32_EMULATION and vsyscall=none linux
2018-02-11 11:10 ` Dominik Brodowski
2018-02-11 11:10 ` [Linux-kselftest-mirror] [PATCH 1/5] selftests/x86: 5lvl test has been moved linux
2018-02-11 11:10 ` Dominik Brodowski
2018-02-11 11:10 ` [Linux-kselftest-mirror] [PATCH 2/5] selftests/x86: fix vDSO selftest segfault for vsyscall=none linux
2018-02-11 11:10 ` Dominik Brodowski
2018-02-11 11:21 ` mingo
2018-02-11 11:21 ` Ingo Molnar
2018-02-11 12:17 ` linux
2018-02-11 12:17 ` Dominik Brodowski
2018-02-11 13:00 ` linux
2018-02-11 13:00 ` Dominik Brodowski
2018-02-11 18:24 ` mingo [this message]
2018-02-11 18:24 ` Ingo Molnar
2018-02-11 20:59 ` [Linux-kselftest-mirror] [PATCH] selftests/x86: clarify that there is no buffer overflow on sscanf usage linux
2018-02-11 20:59 ` Dominik Brodowski
2018-02-12 17:58 ` shuah
2018-02-12 17:58 ` Shuah Khan
2018-02-11 11:10 ` [Linux-kselftest-mirror] [PATCH 3/5] selftests/x86: do not rely on int $0x80 in test_mremap_vdso.c linux
2018-02-11 11:10 ` Dominik Brodowski
2018-02-11 11:10 ` [Linux-kselftest-mirror] [PATCH 4/5] selftests/x86: do not rely on int $0x80 in single_step_syscall.c linux
2018-02-11 11:10 ` Dominik Brodowski
2018-02-11 11:10 ` [Linux-kselftest-mirror] [PATCH 5/5] selftests/x86: disable tests requiring 32bit support on pure 64bit systems linux
2018-02-11 11:10 ` Dominik Brodowski
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