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From: Dominik Brodowski <linux@dominikbrodowski.net>
To: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	x86@kernel.org, shuah@kernel.org,
	Andrew Lutomirski <luto@kernel.org>
Subject: Re: [PATCH 2/5] selftests/x86: fix vDSO selftest segfault for vsyscall=none
Date: Sun, 11 Feb 2018 14:00:29 +0100	[thread overview]
Message-ID: <20180211130029.GA23754@light.dominikbrodowski.net> (raw)
In-Reply-To: <20180211121714.GA11096@isilmar-4.linta.de>

On Sun, Feb 11, 2018 at 01:17:14PM +0100, Dominik Brodowski wrote:
> On Sun, Feb 11, 2018 at 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)) {

Thanks,
	Dominik

WARNING: multiple messages have this Message-ID (diff)
From: linux at dominikbrodowski.net (Dominik Brodowski)
Subject: [Linux-kselftest-mirror] [PATCH 2/5] selftests/x86: fix vDSO selftest segfault for vsyscall=none
Date: Sun, 11 Feb 2018 14:00:29 +0100	[thread overview]
Message-ID: <20180211130029.GA23754@light.dominikbrodowski.net> (raw)
In-Reply-To: <20180211121714.GA11096@isilmar-4.linta.de>

On Sun, Feb 11, 2018 at 01:17:14PM +0100, Dominik Brodowski wrote:
> On Sun, Feb 11, 2018 at 12:21:53PM +0100, Ingo Molnar wrote:
> > 
> > * Dominik Brodowski <linux at 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)) {

Thanks,
	Dominik
--
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WARNING: multiple messages have this Message-ID (diff)
From: linux@dominikbrodowski.net (Dominik Brodowski)
Subject: [Linux-kselftest-mirror] [PATCH 2/5] selftests/x86: fix vDSO selftest segfault for vsyscall=none
Date: Sun, 11 Feb 2018 14:00:29 +0100	[thread overview]
Message-ID: <20180211130029.GA23754@light.dominikbrodowski.net> (raw)
Message-ID: <20180211130029.AY3HyZ9vsGDMwSAH7vaCXOaUzm9UWnpGzP7FLbQ9TIs@z> (raw)
In-Reply-To: <20180211121714.GA11096@isilmar-4.linta.de>

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)) {

Thanks,
	Dominik
--
To unsubscribe from this list: send the line "unsubscribe linux-kselftest" in
the body of a message to majordomo at vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

  reply	other threads:[~2018-02-11 13:00 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-11 11:10 [PATCH 0/5] selftests/x86: fixes for !CONFIG_IA32_EMULATION and vsyscall=none Dominik Brodowski
2018-02-11 11:10 ` [Linux-kselftest-mirror] " Dominik Brodowski
2018-02-11 11:10 ` linux
2018-02-11 11:10 ` [PATCH 1/5] selftests/x86: 5lvl test has been moved Dominik Brodowski
2018-02-11 11:10   ` [Linux-kselftest-mirror] " Dominik Brodowski
2018-02-11 11:10   ` linux
2018-02-11 12:13   ` [tip:x86/urgent] selftests/x86: Fix build bug caused by the 5lvl test which has been moved to the VM directory tip-bot for Dominik Brodowski
2018-02-13  9:05   ` [tip:x86/pti] " tip-bot for Dominik Brodowski
2018-02-11 11:10 ` [PATCH 2/5] selftests/x86: fix vDSO selftest segfault for vsyscall=none Dominik Brodowski
2018-02-11 11:10   ` [Linux-kselftest-mirror] " Dominik Brodowski
2018-02-11 11:10   ` linux
2018-02-11 11:21   ` Ingo Molnar
2018-02-11 11:21     ` [Linux-kselftest-mirror] " Ingo Molnar
2018-02-11 11:21     ` mingo
2018-02-11 12:17     ` Dominik Brodowski
2018-02-11 12:17       ` [Linux-kselftest-mirror] " Dominik Brodowski
2018-02-11 12:17       ` linux
2018-02-11 13:00       ` Dominik Brodowski [this message]
2018-02-11 13:00         ` Dominik Brodowski
2018-02-11 13:00         ` linux
2018-02-11 18:24         ` Ingo Molnar
2018-02-11 18:24           ` [Linux-kselftest-mirror] " Ingo Molnar
2018-02-11 18:24           ` mingo
2018-02-11 20:59           ` [PATCH] selftests/x86: clarify that there is no buffer overflow on sscanf usage Dominik Brodowski
2018-02-11 20:59             ` [Linux-kselftest-mirror] " Dominik Brodowski
2018-02-11 20:59             ` linux
2018-02-12 17:58             ` Shuah Khan
2018-02-12 17:58               ` [Linux-kselftest-mirror] " Shuah Khan
2018-02-12 17:58               ` shuah
2018-02-13  9:04             ` [tip:x86/pti] selftests/x86: Clean up and document sscanf() usage tip-bot for Dominik Brodowski
2018-02-13  9:04   ` [tip:x86/pti] selftests/x86: Fix vDSO selftest segfault for vsyscall=none tip-bot for Dominik Brodowski
2018-02-11 11:10 ` [PATCH 3/5] selftests/x86: do not rely on int $0x80 in test_mremap_vdso.c Dominik Brodowski
2018-02-11 11:10   ` [Linux-kselftest-mirror] " Dominik Brodowski
2018-02-11 11:10   ` linux
2018-02-11 12:13   ` [tip:x86/urgent] selftests/x86: Do not rely on "int $0x80" " tip-bot for Dominik Brodowski
2018-02-13  9:06   ` [tip:x86/pti] " tip-bot for Dominik Brodowski
2018-02-11 11:10 ` [PATCH 4/5] selftests/x86: do not rely on int $0x80 in single_step_syscall.c Dominik Brodowski
2018-02-11 11:10   ` [Linux-kselftest-mirror] " Dominik Brodowski
2018-02-11 11:10   ` linux
2018-02-11 12:14   ` [tip:x86/urgent] selftests/x86: Do not rely on "int $0x80" " tip-bot for Dominik Brodowski
2018-02-13  9:06   ` [tip:x86/pti] " tip-bot for Ingo Molnar
2018-02-15  0:25   ` tip-bot for Dominik Brodowski
2018-02-11 11:10 ` [PATCH 5/5] selftests/x86: disable tests requiring 32bit support on pure 64bit systems Dominik Brodowski
2018-02-11 11:10   ` [Linux-kselftest-mirror] " Dominik Brodowski
2018-02-11 11:10   ` linux
2018-02-11 12:14   ` [tip:x86/urgent] selftests/x86: Disable tests requiring 32-bit support on pure 64-bit systems tip-bot for Dominik Brodowski
2018-02-13  9:07   ` [tip:x86/pti] " tip-bot for Ingo Molnar
2018-02-15  0:25   ` tip-bot for Dominik Brodowski

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