linux-kernel - [PATCH 1/2] sysfs: attribute_group: allow registration of const bin

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20241115-b4-sysfs-const-bin_attr-group-v1-1-2c9bb12dfc48@weissschuh.net>
Date: Fri, 15 Nov 2024 17:42:48 +0100
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 "Rafael J. Wysocki" <rafael@...nel.org>
Cc: linux-kernel@...r.kernel.org, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH 1/2] sysfs: attribute_group: allow registration of const
 bin_attribute

To be able to constify instances of struct bin_attribute it has to be
possible to add them to string attribute_group.
The current type of the bin_attrs member however is not compatible with
that.
Introduce a union that allows registration of both const and non-const
attributes to enable a piecewise transition.
As both union member types are compatible no logic needs to be adapted.

Technically it is now possible register a const struct
bin_attribute and receive it as mutable pointer in the callbacks.
This is a soundness issue.
But this same soundness issue already exists today in
sysfs_create_bin_file().
Also the struct definition and callback implementation are always
closely linked and are meant to be moved to const in lockstep.

Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
 include/linux/sysfs.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index d713a6445a6267145a7014f308df3bb25b8c3287..0f2fcd244523f050c5286f19d4fe1846506f9214 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -106,7 +106,10 @@ struct attribute_group {
 					    const struct bin_attribute *,
 					    int);
 	struct attribute	**attrs;
-	struct bin_attribute	**bin_attrs;
+	union {
+		struct bin_attribute		**bin_attrs;
+		const struct bin_attribute	*const *bin_attrs_new;
+	};
 };

 #define SYSFS_PREALLOC		010000

-- 
2.47.0