From: james.morse@arm•com (James Morse)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCHv2 2/2] arm64: hibernate: handle allocation failures
Date: Fri, 12 Aug 2016 19:07:27 +0100 [thread overview]
Message-ID: <57AE105F.2050800@arm.com> (raw)
In-Reply-To: <1470921066-27421-3-git-send-email-mark.rutland@arm.com>
On 11/08/16 14:11, Mark Rutland wrote:
> In create_safe_exec_page(), we create a copy of the hibernate exit text,
> along with some page tables to map this via TTBR0. We then install the
> new tables in TTBR0.
>
> In swsusp_arch_resume() we call create_safe_exec_page() before trying a
> number of operations which may fail (e.g. copying the linear map page
> tables). If these fail, we bail out of swsusp_arch_resume() and return
> an error code, but leave TTBR0 as-is. Subsequently, the core hibernate
> code will call free_basic_memory_bitmaps(), which will free all of the
> memory allocations we made, including the page tables installed in
> TTBR0.
>
> Thus, we may have TTBR0 pointing at dangling freed memory for some
> period of time. If the hibernate attempt was triggered by a user
> requesting a hibernate test via the reboot syscall, we may return to
> userspace with the clobbered TTBR0 value.
>
> Avoid these issues by reorganising swsusp_arch_resume() such that we
> have no failure paths after create_safe_exec_page(). We also add a check
> that the zero page allocation succeeded, matching what we have for other
> allocations.
Looks good to me.
Acked-by: James Morse <james.morse@arm•com>
Thanks,
James
prev parent reply other threads:[~2016-08-12 18:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-11 13:11 [PATCHv2 0/2] arm64: hibernate: a couple of fixes Mark Rutland
2016-08-11 13:11 ` [PATCHv2 1/2] arm64: hibernate: avoid potential TLB conflict Mark Rutland
2016-08-11 13:11 ` [PATCHv2 2/2] arm64: hibernate: handle allocation failures Mark Rutland
2016-08-12 18:07 ` James Morse [this message]
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