[PATCH] modinfo: don't parse built-in for explicitly given module files

A recent bug report showed that modinfo doesn't give the signature
information for certain modules, and it turned out to happen only on
the modules that are built-in on the running kernel; then modinfo
skips the signature check, as if the target module file never exists.
The behavior is, however, inconsistent when modinfo is performed for
external modules (no matter which kernel version is) and the module
file path is explicitly given by a command-line argument, which
guarantees the presence of the module file itself.

This patch addresses the regression by checking the presence of the
module path at first before checking the built-in module.

Fixes: e7e2cb61fa9f ("modinfo: Show information about built-in modules")
BugLink: https://bugzilla.opensuse.org/show_bug.cgi?id=1189537
Signed-off-by: Takashi Iwai <redacted>
---
 libkmod/libkmod-module.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libkmod/libkmod-module.c b/libkmod/libkmod-module.c
index 6e0ff1a99604..9e878a5345a1 100644
--- a/libkmod/libkmod-module.c
+++ b/libkmod/libkmod-module.c

@@ -2292,7 +2292,8 @@ KMOD_EXPORT int kmod_module_get_info(const struct kmod_module *mod, struct kmod_
 	assert(*list == NULL);
 
 	/* remove const: this can only change internal state */
-	if (kmod_module_is_builtin((struct kmod_module *)mod)) {
+	if (!kmod_module_get_path(mod) &&
+	    kmod_module_is_builtin((struct kmod_module *)mod)) {
 		count = kmod_builtin_get_modinfo(mod->ctx,
 						kmod_module_get_name(mod),
 						&strings);

-- 
2.26.2

On Wed, Aug 18, 2021 at 01:22:03PM +0200, Takashi Iwai wrote:

A recent bug report showed that modinfo doesn't give the signature
information for certain modules, and it turned out to happen only on
the modules that are built-in on the running kernel; then modinfo
skips the signature check, as if the target module file never exists.
The behavior is, however, inconsistent when modinfo is performed for
external modules (no matter which kernel version is) and the module
file path is explicitly given by a command-line argument, which
guarantees the presence of the module file itself.

This patch addresses the regression by checking the presence of the
module path at first before checking the built-in module.

Fixes: e7e2cb61fa9f ("modinfo: Show information about built-in modules")
BugLink: https://bugzilla.opensuse.org/show_bug.cgi?id=1189537
Signed-off-by: Takashi Iwai <redacted>

Reviewed-by: Michal Suchánek <redacted>

LGTM

Thanks

Hi,

Reviewed-by: Petr Vorel <pvorel@suse.cz>

Kind regards,
Petr

On Wed, Aug 18, 2021 at 4:23 AM Takashi Iwai [off-list ref] wrote:

thanks for spotting this... but I'm not sure this is the right fix.
kmod_module_is_builtin() shouldn't return true if the module was
created by path rather than lookup. It seems we should rather set
mod->builtin = KMOD_MODULE_BUILTIN_NO in
kmod_module_new_from_path(). This would also fix the use of
kmod_module_is_builtin() directly by applications.

Since the builtin check uses lazy initialization,  the default is
KMOD_MODULE_BUILTIN_UNKNOWN, hence the bug here.

Lucas De Marchi

                count = kmod_builtin_get_modinfo(mod->ctx,
                                                kmod_module_get_name(mod),
                                                &strings);
--
2.26.2

Something like this?

Thanks

Michal

--------------------------------------------------------------------

A recent bug report showed that modinfo doesn't give the signature
information for certain modules, and it turned out to happen only on
the modules that are built-in on the running kernel; then modinfo
skips the signature check, as if the target module file never exists.
The behavior is, however, inconsistent when modinfo is performed for
external modules (no matter which kernel version is) and the module
file path is explicitly given by a command-line argument, which
guarantees the presence of the module file itself.

Fixes: e7e2cb61fa9f ("modinfo: Show information about built-in modules")
Link: https://lore.kernel.org/linux-modules/CAKi4VAJVvY3=JdSZm-GD1hJqyCPYaYz-jBJ_REeY5BakVb6_ww@mail.gmail.com/
BugLink: https://bugzilla.opensuse.org/show_bug.cgi?id=1189537
Suggested-by: Lucas De Marchi <redacted>
Signed-off-by: Michal Suchanek <redacted>
---
 libkmod/libkmod-module.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/libkmod/libkmod-module.c b/libkmod/libkmod-module.c
index 9e878a5345a1..53b220d492e8 100644
--- a/libkmod/libkmod-module.c
+++ b/libkmod/libkmod-module.c

@@ -432,18 +432,18 @@ KMOD_EXPORT int kmod_module_new_from_path(struct kmod_ctx *ctx,
 		}
 
 		*mod = kmod_module_ref(m);
-		return 0;
-	}
+	} else {
+		err = kmod_module_new(ctx, name, name, namelen, NULL, 0, &m);
+		if (err < 0) {
+			free(abspath);
+			return err;
+		}
 
-	err = kmod_module_new(ctx, name, name, namelen, NULL, 0, &m);
-	if (err < 0) {
-		free(abspath);
-		return err;
+		m->path = abspath;
+		*mod = m;
 	}
 
-	m->path = abspath;
-	*mod = m;
-
+	(*mod)->builtin = KMOD_MODULE_BUILTIN_NO;
 	return 0;
 }
 

-- 
2.31.1

On Wed, Aug 18, 2021 at 1:53 PM Michal Suchanek [off-list ref] wrote:

Something like this?

yep. Just a matter of style but I think I like the *mod = m as the
last thing. Let me send it with that additional change.

thanks
Lucas De Marchi

From: Michal Suchanek <redacted>

A recent bug report showed that modinfo doesn't give the signature
information for certain modules, and it turned out to happen only on
the modules that are built-in on the running kernel; then modinfo
skips the signature check, as if the target module file never exists.
The behavior is, however, inconsistent when modinfo is performed for
external modules (no matter which kernel version is) and the module
file path is explicitly given by a command-line argument, which
guarantees the presence of the module file itself.

Fixes: e7e2cb61fa9f ("modinfo: Show information about built-in modules")
Link: https://lore.kernel.org/linux-modules/CAKi4VAJVvY3=JdSZm-GD1hJqyCPYaYz-jBJ_REeY5BakVb6_ww@mail.gmail.com/
BugLink: https://bugzilla.opensuse.org/show_bug.cgi?id=1189537
Suggested-by: Lucas De Marchi <redacted>
Signed-off-by: Michal Suchanek <redacted>
---
 libkmod/libkmod-module.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/libkmod/libkmod-module.c b/libkmod/libkmod-module.c
index 6e0ff1a..6f7747c 100644
--- a/libkmod/libkmod-module.c
+++ b/libkmod/libkmod-module.c

@@ -431,17 +431,18 @@ KMOD_EXPORT int kmod_module_new_from_path(struct kmod_ctx *ctx,
 			return -EEXIST;
 		}
 
-		*mod = kmod_module_ref(m);
-		return 0;
-	}
+		kmod_module_ref(m);
+	} else {
+		err = kmod_module_new(ctx, name, name, namelen, NULL, 0, &m);
+		if (err < 0) {
+			free(abspath);
+			return err;
+		}
 
-	err = kmod_module_new(ctx, name, name, namelen, NULL, 0, &m);
-	if (err < 0) {
-		free(abspath);
-		return err;
+		m->path = abspath;
 	}
 
-	m->path = abspath;
+	m->builtin = KMOD_MODULE_BUILTIN_NO;
 	*mod = m;
 
 	return 0;

-- 
2.31.1

From: Michal Suchanek <redacted>

A recent bug report showed that modinfo doesn't give the signature
information for certain modules, and it turned out to happen only on
the modules that are built-in on the running kernel; then modinfo
skips the signature check, as if the target module file never exists.
The behavior is, however, inconsistent when modinfo is performed for
external modules (no matter which kernel version is) and the module
file path is explicitly given by a command-line argument, which
guarantees the presence of the module file itself.

Fixes: e7e2cb61fa9f ("modinfo: Show information about built-in modules")
Link: https://lore.kernel.org/linux-modules/CAKi4VAJVvY3=JdSZm-GD1hJqyCPYaYz-jBJ_REeY5BakVb6_ww@mail.gmail.com/
BugLink: https://bugzilla.opensuse.org/show_bug.cgi?id=1189537
Suggested-by: Lucas De Marchi <redacted>
Signed-off-by: Michal Suchanek <redacted>
---
 libkmod/libkmod-module.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/libkmod/libkmod-module.c b/libkmod/libkmod-module.c
index 6e0ff1a..6f7747c 100644
--- a/libkmod/libkmod-module.c
+++ b/libkmod/libkmod-module.c

@@ -431,17 +431,18 @@ KMOD_EXPORT int kmod_module_new_from_path(struct kmod_ctx *ctx,
 			return -EEXIST;
 		}
 
-		*mod = kmod_module_ref(m);
-		return 0;
-	}
+		kmod_module_ref(m);
+	} else {
+		err = kmod_module_new(ctx, name, name, namelen, NULL, 0, &m);
+		if (err < 0) {
+			free(abspath);
+			return err;
+		}
 
-	err = kmod_module_new(ctx, name, name, namelen, NULL, 0, &m);
-	if (err < 0) {
-		free(abspath);
-		return err;
+		m->path = abspath;
 	}
 
-	m->path = abspath;
+	m->builtin = KMOD_MODULE_BUILTIN_NO;
 	*mod = m;
 
 	return 0;

-- 
2.31.1

Hi all,

Reviewed-by: Petr Vorel <pvorel@suse.cz>

Kind regards,
Petr