linux-kernel - Re: [PATCH v2 1/6] aarch64: Fix missing BTI protection from dependencies [BZ #26926]

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Message-ID: <20201211153334.GF24625@arm.com>
Date:   Fri, 11 Dec 2020 15:33:34 +0000
From:   Szabolcs Nagy <szabolcs.nagy@....com>
To:     Adhemerval Zanella <adhemerval.zanella@...aro.org>
Cc:     libc-alpha@...rceware.org, Mark Rutland <mark.rutland@....com>,
        kernel-hardening@...ts.openwall.com,
        Catalin Marinas <catalin.marinas@....com>,
        linux-kernel@...r.kernel.org,
        Jeremy Linton <jeremy.linton@....com>,
        Mark Brown <broonie@...nel.org>,
        Topi Miettinen <toiwoton@...il.com>,
        Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 1/6] aarch64: Fix missing BTI protection from
 dependencies [BZ #26926]

The 12/10/2020 14:51, Adhemerval Zanella wrote:
> On 27/11/2020 10:19, Szabolcs Nagy via Libc-alpha wrote:
> > The _dl_open_check and _rtld_main_check hooks are not called on the
> > dependencies of a loaded module, so BTI protection was missed on
> > every module other than the main executable and directly dlopened
> > libraries.
> > 
> > The fix just iterates over dependencies to enable BTI.
> > 
> > Fixes bug 26926.
> 
> LGTM, modulus the argument name change.
> 
> I also think it would be better to add a testcase, for both DT_NEEDED
> and dlopen case.

thanks, i committed this with fixed argument name as attached.

i plan to do tests later once i understand the BTI semantics
(right now it's not clear if in the presence of some W^X
policy BTI may be silently ignored or not).

View attachment "0001-aarch64-Fix-missing-BTI-protection-from-dependencies.patch" of type "text/x-diff" (1448 bytes)