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From: Masahiro Yamada <yamada.masahiro@socionext.com>
To: Jessica Yu <jeyu@kernel.org>
Cc: Matthias Maennich <maennich@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Joel Fernandes <joel@joelfernandes.org>,
	Martijn Coenen <maco@android.com>,
	Will Deacon <will.deacon@arm.com>,
	Michal Marek <michal.lkml@markovi.net>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/7] modpost: fix broken sym->namespace for external module builds
Date: Fri, 27 Sep 2019 18:56:55 +0900	[thread overview]
Message-ID: <CAK7LNATamQYGDj0CQCn6Fg-+tNykfGqFzhjFxUyoGYxn2DSKgA@mail.gmail.com> (raw)
In-Reply-To: <20190927093603.9140-2-yamada.masahiro@socionext.com>

On Fri, Sep 27, 2019 at 6:37 PM Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
>
> Currently, external module builds produce tons of false-positives:
>
>   WARNING: module <mod> uses symbol <sym> from namespace <ns>, but does not import it.
>
> Here, the <ns> part shows a random string.
>
> When you build external modules, the symbol info of vmlinux and
> in-kernel modules are read from $(objtree)/Module.symvers, but
> read_dump() is buggy in multiple ways:
>
> [1] When the modpost is run for vmlinux and in-kernel modules,
> sym_extract_namespace() correctly allocates memory for the namespace.
> On the other hand, read_dump() does not, then sym->namespace will
> point to somewhere in the line buffer of get_next_line(). The data
> in the buffer will be replaced soon, and sym->namespace will end up
> with pointing to unrelated data. As a result, check_exports() will
> show random strings in the warning messages.
>
> [2] When there is no namespace, sym_extract_namespace() returns NULL.
> On the other hand, read_dump() sets namespace to an empty string "".
> (but, it will be later replaced with unrelated data due to bug [1].)
> The check_exports() shows a warning unless exp->namespace is NULL,
> so every symbol read from read_dump() emits the warning, which is
> mostly false positive.
>
> To address [1], I added NOFAIL(strdup(...)) to allocate memory.
> For [2], I changed the if-conditional in check_exports().
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
>

Fixes: cb9b55d21fe0 ("modpost: add support for symbol namespaces")


-- 
Best Regards
Masahiro Yamada

  reply	other threads:[~2019-09-27  9:58 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-27  9:35 [PATCH 0/7] module: various bug-fixes and clean-ups for module namespace Masahiro Yamada
2019-09-27  9:35 ` [PATCH 1/7] modpost: fix broken sym->namespace for external module builds Masahiro Yamada
2019-09-27  9:56   ` Masahiro Yamada [this message]
2019-09-27 11:46   ` Matthias Maennich
2019-09-27  9:35 ` [PATCH 2/7] module: swap the order of symbol.namespace Masahiro Yamada
2019-09-27 12:07   ` Matthias Maennich
2019-09-27  9:35 ` [PATCH 3/7] module: rename __kstrtab_ns_* to __kstrtabns_* to avoid symbol conflict Masahiro Yamada
2019-09-27 12:14   ` Matthias Maennich
2019-09-27  9:36 ` [PATCH 4/7] module: avoid code duplication in include/linux/export.h Masahiro Yamada
2019-09-27  9:58   ` Masahiro Yamada
2019-09-27 11:07   ` Rasmus Villemoes
2019-09-27 12:36     ` Matthias Maennich
2019-10-29 19:19     ` Jessica Yu
2019-10-29 21:11       ` Rasmus Villemoes
2019-10-31 10:13         ` Jessica Yu
2019-10-31 11:03           ` Rasmus Villemoes
2019-10-31 11:26             ` Jessica Yu
2019-09-27  9:36 ` [PATCH 5/7] kbuild: fix build error of 'make nsdeps' in clean tree Masahiro Yamada
2019-09-27 12:44   ` Matthias Maennich
2019-09-27  9:36 ` [PATCH 6/7] nsdeps: fix hashbang of scripts/nsdeps Masahiro Yamada
2019-09-27 13:10   ` Matthias Maennich
2019-09-27  9:36 ` [PATCH 7/7] nsdeps: make generated patches independent of locale Masahiro Yamada
2019-09-27 13:27   ` Matthias Maennich
2019-09-27 15:42     ` Masahiro Yamada
2019-09-27 18:14       ` Greg Kroah-Hartman
2019-09-29  1:18         ` Masahiro Yamada
2019-09-29  1:30           ` Masahiro Yamada
2019-10-01 11:46             ` Matthias Maennich
2019-09-29 10:14           ` Greg Kroah-Hartman
2019-09-27 13:41 ` [PATCH 0/7] module: various bug-fixes and clean-ups for module namespace Matthias Maennich
2019-09-27 15:43   ` Masahiro Yamada
2019-10-02 18:57   ` Jessica Yu
2019-10-02 20:43     ` Matthias Maennich
2019-10-03  1:26     ` Masahiro Yamada
2019-10-03  8:03     ` Masahiro Yamada

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