[PATCH v2] modpost: abort if a module symbol is too long

From: Takashi Iwai
Date: Fri Aug 07 2015 - 02:55:54 EST


Module symbols have a limited length, but currently the build system
allows the build finishing even if the driver code contains a too long
symbol name, which eventually overflows the modversion_info[] item.
The compiler may catch at compiling *.mod.c like
CC xxx.mod.o
xxx.mod.c:18:16: warning: initializer-string for array of chars is too long
but it's merely a warning.

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

Currently MODULE_NAME_LEN is defined in modpost.c instead of referring
to the definition in kernel header because including linux/module.h is
messy and we must cover cross-compilation.

Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
v1->v2: Fix MODULE_NAME_LEN to use Elf_Addr

scripts/mod/modpost.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 12d3db3bd46b..d583c98fde31 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2133,6 +2133,11 @@ 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
**/
@@ -2177,6 +2182,12 @@ static int add_versions(struct buffer *b, struct module *mod)
s->name, mod->name);
continue;
}
+ if (strlen(s->name) >= MODULE_NAME_LEN) {
+ merror("too long symbol \"%s\" [%s.ko]\n",
+ s->name, mod->name);
+ err = 1;
+ break;
+ }
buf_printf(b, "\t{ %#8x, __VMLINUX_SYMBOL_STR(%s) },\n",
s->crc, s->name);
}
--
2.5.0

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