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authorMasahiro Yamada <yamada.masahiro@socionext.com>2019-10-03 16:58:22 +0900
committerJessica Yu <jeyu@kernel.org>2019-10-07 18:24:58 +0200
commit389eb3f5f4abbdb9810458ac9b87427336ba5b91 (patch)
tree5f9dea737c290bfc7aefb4d19f8c039ab9e4d467 /scripts/mod
parentbf70b0503abd19194dba25fe383d143d0229dc6a (diff)
downloadlinux-389eb3f5f4abbdb9810458ac9b87427336ba5b91.tar.bz2
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 'scripts/mod')
-rw-r--r--scripts/mod/modpost.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index c4b536ac1327..4d2cdb4d71e3 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -166,7 +166,7 @@ struct symbol {
struct module *module;
unsigned int crc;
int crc_valid;
- const char *namespace;
+ char *namespace;
unsigned int weak:1;
unsigned int vmlinux:1; /* 1 if symbol is defined in vmlinux */
unsigned int kernel:1; /* 1 if symbol is from kernel
@@ -348,7 +348,7 @@ static enum export export_from_sec(struct elf_info *elf, unsigned int sec)
return export_unknown;
}
-static const char *sym_extract_namespace(const char **symname)
+static char *sym_extract_namespace(const char **symname)
{
char *namespace = NULL;
char *ns_separator;
@@ -373,7 +373,6 @@ static struct symbol *sym_add_exported(const char *name, const char *namespace,
if (!s) {
s = new_symbol(name, mod, export);
- s->namespace = namespace;
} else {
if (!s->preloaded) {
warn("%s: '%s' exported twice. Previous export was in %s%s\n",
@@ -384,6 +383,8 @@ static struct symbol *sym_add_exported(const char *name, const char *namespace,
s->module = mod;
}
}
+ free(s->namespace);
+ s->namespace = namespace ? strdup(namespace) : NULL;
s->preloaded = 0;
s->vmlinux = is_vmlinux(mod->name);
s->kernel = 0;
@@ -670,7 +671,8 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
unsigned int crc;
enum export export;
bool is_crc = false;
- const char *name, *namespace;
+ const char *name;
+ char *namespace;
if ((!is_vmlinux(mod->name) || mod->is_dot_o) &&
strstarts(symname, "__ksymtab"))
@@ -745,6 +747,7 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
name = symname + strlen("__ksymtab_");
namespace = sym_extract_namespace(&name);
sym_add_exported(name, namespace, mod, export);
+ free(namespace);
}
if (strcmp(symname, "init_module") == 0)
mod->has_init = 1;
@@ -2193,7 +2196,7 @@ 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);