diff options
author | Masahiro Yamada <yamada.masahiro@socionext.com> | 2019-10-03 10:58:22 +0300 |
---|---|---|
committer | Jessica Yu <jeyu@kernel.org> | 2019-10-07 19:24:58 +0300 |
commit | 389eb3f5f4abbdb9810458ac9b87427336ba5b91 (patch) | |
tree | 5f9dea737c290bfc7aefb4d19f8c039ab9e4d467 /block | |
parent | bf70b0503abd19194dba25fe383d143d0229dc6a (diff) | |
download | linux-389eb3f5f4abbdb9810458ac9b87427336ba5b91.tar.xz |
modpost: fix broken sym->namespace for external module builds
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() 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], sym_add_exported() calls strdup() for s->namespace.
The namespace from sym_extract_namespace() must be freed to avoid
memory leak.
For [2], I changed the if-conditional in check_exports().
This commit also fixes sym_add_exported() to set s->namespace correctly
when the symbol is preloaded.
Reviewed-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Diffstat (limited to 'block')
0 files changed, 0 insertions, 0 deletions