From: Mark Rutland <mark.rutland@arm.com>
To: Jinbum Park <jinb.park7@gmail.com>
Cc: linux@armlinux.org.uk, will.deacon@arm.com, mingo@kernel.org,
andy.gross@linaro.org, keescook@chromium.org,
vladimir.murzin@arm.com, f.fainelli@gmail.com,
pawel.moll@arm.com, jonathan.austin@arm.com,
ard.biesheuvel@linaro.org, labbott@redhat.com,
arjan@linux.intel.com, paul.gortmaker@windriver.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
kernel-hardening@lists.openwall.com,
kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] ARM: mm: add testcases for RODATA
Date: Wed, 18 Jan 2017 14:38:17 +0000 [thread overview]
Message-ID: <20170118143815.GG3231@leverpostej> (raw)
In-Reply-To: <20170118135310.GA4733@pjb1027-Latitude-E5410>
On Wed, Jan 18, 2017 at 10:53:10PM +0900, Jinbum Park wrote:
> This patch adds testcases for the CONFIG_DEBUG_RODATA option.
> It's similar to x86's testcases.
> It tests read-only mapped data and page-size aligned rodata section.
I note that LKDTM already has a similar test (though it just has a raw
write, and will crash the kernel).
> + asm volatile(
> + "0: str %[zero], [%[rodata_test]]\n"
> + " mov %[rslt], %[zero]\n"
> + "1:\n"
> + ".pushsection .text.fixup,\"ax\"\n"
> + ".align 2\n"
> + "2:\n"
> + "b 1b\n"
> + ".popsection\n"
> + ".pushsection __ex_table,\"a\"\n"
> + ".align 3\n"
> + ".long 0b, 2b\n"
> + ".popsection\n"
> + : [rslt] "=r" (result)
> + : [zero] "r" (0UL), [rodata_test] "r" (&rodata_test_data)
> + );
This is the only architecture-specific part of the file.
Rather than duplicating the logic from x86, can't we use generic
infrastructure for this part, and move the existing test into a shared
location?
e.g. could we change to KERNEL_DS and use put_user here?
> + if (!result) {
> + pr_err("rodata_test: test data was not read only\n");
> + return -ENODEV;
> + }
> +
> + /* test 3: check the value hasn't changed */
> + /* If this test fails, we managed to overwrite the data */
> + if (!rodata_test_data) {
> + pr_err("rodata_test: Test 3 fails (end data)\n");
> + return -ENODEV;
> + }
> +
> + /* test 4: check if the rodata section is 4Kb aligned */
> + start = (unsigned long)__start_rodata;
> + end = (unsigned long)__end_rodata;
> + if (start & (PAGE_SIZE - 1)) {
> + pr_err("rodata_test: .rodata is not 4k aligned\n");
> + return -ENODEV;
> + }
> + if (end & (PAGE_SIZE - 1)) {
> + pr_err("rodata_test: .rodata end is not 4k aligned\n");
> + return -ENODEV;
> + }
s/4k/page/ in the prints, if this becomes generic.
Thanks,
Mark.
next prev parent reply other threads:[~2017-01-18 14:40 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-18 13:53 [PATCH] ARM: mm: add testcases for RODATA Jinbum Park
2017-01-18 14:38 ` Mark Rutland [this message]
2017-01-18 19:20 ` Laura Abbott
2017-01-18 21:20 ` Kees Cook
2017-01-18 22:36 ` Russell King - ARM Linux
2017-01-18 23:35 ` Kees Cook
2017-01-18 23:38 ` [kernel-hardening] " Laura Abbott
2017-01-18 23:45 ` Russell King - ARM Linux
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