Re: [PATCH v2] modpost: abort if module name is too long

From: Jessica Yu
Date: Tue Jul 04 2017 - 17:45:32 EST


+++ Wanlong Gao [30/06/17 22:07 +0800]:
Module name has a limited length, but currently the build system
allows the build finishing even if the module name is too long.

CC /root/kprobe_example/abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz.mod.o
/root/kprobe_example/abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz.mod.c:9:2:
warning: initializer-string for array of chars is too long [enabled by default]
.name = KBUILD_MODNAME,
^

but it's merely a warning.

This patch adds the check of the module name length in modpost and stops
the build properly.

Signed-off-by: Wanlong Gao <wanlong.gao@xxxxxxxxx>

I have this patch queued up to be applied right after the current
merge window. Thanks!

Jessica

scripts/mod/modpost.c | 29 ++++++++++++++++++++++++-----
1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 30d752a..cb16985 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -47,6 +47,12 @@ enum export {
export_unused_gpl, export_gpl_future, export_unknown
};

+/* In kernel, this size is defined in linux/module.h;
+ * here we use Elf_Addr instead of long for covering cross-compile
+ */
+
+#define MODULE_NAME_LEN (64 - sizeof(Elf_Addr))
+
#define PRINTF __attribute__ ((format (printf, 1, 2)))

PRINTF void fatal(const char *fmt, ...)
@@ -2116,6 +2122,23 @@ static void check_exports(struct module *mod)
}
}

+static int check_modname_len(struct module *mod)
+{
+ const char *mod_name;
+
+ mod_name = strrchr(mod->name, '/');
+ if (mod_name == NULL)
+ mod_name = mod->name;
+ else
+ mod_name++;
+ if (strlen(mod_name) >= MODULE_NAME_LEN) {
+ merror("module name is too long [%s.ko]\n", mod->name);
+ return 1;
+ }
+
+ return 0;
+}
+
/**
* Header for the generated file
**/
@@ -2154,11 +2177,6 @@ static void add_staging_flag(struct buffer *b, const char *name)
buf_printf(b, "\nMODULE_INFO(staging, \"Y\");\n");
}

-/* In kernel, this size is defined in linux/module.h;
- * here we use Elf_Addr instead of long for covering cross-compile
- */
-#define MODULE_NAME_LEN (64 - sizeof(Elf_Addr))
-
/**
* Record CRCs for unresolved symbols
**/
@@ -2489,6 +2507,7 @@ int main(int argc, char **argv)

buf.pos = 0;

+ err |= check_modname_len(mod);
add_header(&buf, mod);
add_intree_flag(&buf, !external_module);
add_staging_flag(&buf, mod->name);
--
2.9.4