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>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Michal Marek <michal.lkml@markovi.net>,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 1/7] modpost: fix broken sym->namespace for external module builds
Date: Fri, 27 Sep 2019 18:35:57 +0900 [thread overview]
Message-ID: <20190927093603.9140-2-yamada.masahiro@socionext.com> (raw)
In-Reply-To: <20190927093603.9140-1-yamada.masahiro@socionext.com>
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>
---
scripts/mod/modpost.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 3961941e8e7a..5c628a7d80f7 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2195,7 +2195,7 @@ static int check_exports(struct module *mod)
else
basename = mod->name;
- if (exp->namespace) {
+ if (exp->namespace && exp->namespace[0]) {
add_namespace(&mod->required_namespaces,
exp->namespace);
@@ -2453,7 +2453,7 @@ static void read_dump(const char *fname, unsigned int kernel)
mod = new_module(modname);
mod->skip = 1;
}
- s = sym_add_exported(symname, namespace, mod,
+ s = sym_add_exported(symname, NOFAIL(strdup(namespace)), mod,
export_no(export));
s->kernel = kernel;
s->preloaded = 1;
--
2.17.1
next prev parent reply other threads:[~2019-09-27 9:37 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 ` Masahiro Yamada [this message]
2019-09-27 9:56 ` [PATCH 1/7] modpost: fix broken sym->namespace for external module builds Masahiro Yamada
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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