netdev - [PATCH] [net] nvmem: disallow modular CONFIG

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-next>] [day] [month] [year] [list]

Date:   Wed,  4 Apr 2018 12:38:40 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Mike Looijmans <mike.looijmans@...ic.nl>,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Oleksij Rempel <o.rempel@...gutronix.de>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] [net] nvmem: disallow modular CONFIG_NVMEM

The new of_get_nvmem_mac_address() helper function causes a link error
with CONFIG_NVMEM=m:

drivers/of/of_net.o: In function `of_get_nvmem_mac_address':
of_net.c:(.text+0x168): undefined reference to `of_nvmem_cell_get'
of_net.c:(.text+0x19c): undefined reference to `nvmem_cell_read'
of_net.c:(.text+0x1a8): undefined reference to `nvmem_cell_put'

I could not come up with a good solution for this, as the code is always
built-in. Using an #if IS_REACHABLE() check around it would solve the
link time issue but then stop it from working in that configuration.
Making of_nvmem_cell_get() an inline function could also solve that, but
seems a bit ugly since it's somewhat larger than most inline functions,
and it would just bring that problem into the callers.  Splitting the
function into a separate file might be an alternative.

This uses the big hammer by making CONFIG_NVMEM itself a 'bool' symbol,
which avoids the problem entirely but makes the vmlinux larger for anyone
that might use NVMEM support but doesn't need it built-in otherwise.

Fixes: 9217e566bdee ("of_net: Implement of_get_nvmem_mac_address helper")
Cc: Mike Looijmans <mike.looijmans@...ic.nl>
Cc: Florian Fainelli <f.fainelli@...il.com>
Cc: Andrew Lunn <andrew@...n.ch>
Cc: David S. Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
The problem arrived through the networking tree, but it's now in
mainline, so the fix could go through either tree
---
 drivers/nvmem/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 5f9bc787d634..1090924efdb1 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -1,5 +1,5 @@
 menuconfig NVMEM
-	tristate "NVMEM Support"
+	bool "NVMEM Support"
 	help
 	  Support for NVMEM(Non Volatile Memory) devices like EEPROM, EFUSES...

-- 
2.9.0