From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: READ_IMPLIES_EXEC set when no GNU_STACK header present
Date: Tue, 3 Aug 2010 21:02:34 +0100 [thread overview]
Message-ID: <20100803200234.GB28048@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20100803195816.GB31111@ubuntu-workstation>
On Tue, Aug 03, 2010 at 02:58:16PM -0500, Seth Forshee wrote:
> We recently noticed that all of our applications had the execute
> permission set for any mappings with read permission on an ARMv6
> platform. This is happening because the ELF images do not have a
> GNU_STACK program header, causing executable_stack=EXSTACK_DEFAULT to be
> passed to arm_elf_read_implies_exec(), and it immediately returns 1.
That's correct behaviour. Historically, ARM ELF binaries don't have
the GNU_STACK program header, but expect read+exec behaviour from the
stack.
> [ARM] enable NX support by default
>
> arm_elf_read_implies_exec() currently returns 1 unless non-
> executable stacks are explicitly requested. This results in
> READ_IMPLIES_EXEC being set for elf images without a GNU_STACK
> program header, even though executable stacks aren't actually
> being requested. This function should default to enabling NX when
> the architecture supports it for better security.
NAK. If you want NX, you must ensure that your applications are built
correctly.
next prev parent reply other threads:[~2010-08-03 20:02 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-03 19:58 READ_IMPLIES_EXEC set when no GNU_STACK header present Seth Forshee
2010-08-03 20:02 ` Russell King - ARM Linux [this message]
2010-08-03 20:04 ` Seth Forshee
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