From: dave.long@linaro.org (David Long)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] arm64: kprobes: Remove unneeded address sanity check
Date: Wed, 14 Feb 2018 21:08:03 -0500 [thread overview]
Message-ID: <5A84EB83.7070807@linaro.org> (raw)
In-Reply-To: <20180201093459.20477-2-takahiro.akashi@linaro.org>
On 02/01/2018 04:34 AM, AKASHI Takahiro wrote:
> From: Masami Hiramatsu <mhiramat@kernel.org>
>
> Remove unneeded address sanity check in arch_prepare_kprobe().
> Since do_debug_exception() is already blacklisted for kprobes, no need
> to reject all __exception functions. Also, since generic kprobe
> framework already ensures the address is in kernel text, no need to
> check it is in rodata again.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> Reported-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> ---
> arch/arm64/kernel/probes/kprobes.c | 8 --------
> 1 file changed, 8 deletions(-)
>
> diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
> index d849d9804011..3c487a389252 100644
> --- a/arch/arm64/kernel/probes/kprobes.c
> +++ b/arch/arm64/kernel/probes/kprobes.c
> @@ -78,8 +78,6 @@ static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs)
> int __kprobes arch_prepare_kprobe(struct kprobe *p)
> {
> unsigned long probe_addr = (unsigned long)p->addr;
> - extern char __start_rodata[];
> - extern char __end_rodata[];
>
> if (probe_addr & 0x3)
> return -EINVAL;
> @@ -87,12 +85,6 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
> /* copy instruction */
> p->opcode = le32_to_cpu(*p->addr);
>
> - if (in_exception_text(probe_addr))
> - return -EINVAL;
> - if (probe_addr >= (unsigned long) __start_rodata &&
> - probe_addr <= (unsigned long) __end_rodata)
> - return -EINVAL;
> -
> /* decode instruction */
> switch (arm_kprobe_decode_insn(p->addr, &p->ainsn)) {
> case INSN_REJECTED: /* insn not supported */
>
I have tested this change on v4.15 using kprobes events and I find it
allows kprobes to be placed in exception text when they were previously
rejected. Is there some other recent change I need to test this with for
the previous behavior to be preserved?
-dl
next prev parent reply other threads:[~2018-02-15 2:08 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-01 9:34 [PATCH 0/2] lkdtm: fix irq handler entry for arm64 AKASHI Takahiro
2018-02-01 9:34 ` [PATCH 1/2] arm64: kprobes: Remove unneeded address sanity check AKASHI Takahiro
2018-02-06 14:36 ` Will Deacon
2018-02-07 0:02 ` Masami Hiramatsu
2018-02-15 2:08 ` David Long [this message]
2018-02-15 6:47 ` Masami Hiramatsu
2018-02-22 5:19 ` David Long
2018-02-22 5:45 ` Masami Hiramatsu
2018-02-01 9:34 ` [PATCH 2/2] lkdtm: fix irq handler entry for arm64 AKASHI Takahiro
2018-02-27 3:57 ` Kees Cook
2018-02-27 5:07 ` Masami Hiramatsu
2018-02-27 7:20 ` AKASHI Takahiro
2018-02-27 15:46 ` Kees Cook
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