net: ipv6: unexport __init-annotated seg6_hmac_init()

BugLink: https://bugs.launchpad.net/bugs/1982968
[ Upstream commit 5801f064e35181c71857a80ff18af4dbec3c5f5c ]

EXPORT_SYMBOL and __init is a bad combination because the .init.text
section is freed up after the initialization. Hence, modules cannot
use symbols annotated __init. The access to a freed symbol may end up
with kernel panic.

modpost used to detect it, but it has been broken for a decade.

Recently, I fixed modpost so it started to warn it again, then this
showed up in linux-next builds.

There are two ways to fix it:

  - Remove __init
  - Remove EXPORT_SYMBOL

I chose the latter for this case because the caller (net/ipv6/seg6.c)
and the callee (net/ipv6/seg6_hmac.c) belong to the same module.
It seems an internal function call in ipv6.ko.

Fixes: bf355b8d2c30 ("ipv6: sr: add core files for SR HMAC support")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/net/ipv6/seg6_hmac.c b/net/ipv6/seg6_hmac.c
index 687d95dce08522bebf6d0c3b0473cb8eb3f2a17d..5b2c9ce533951edcda7ea54fab29bf88dd3e90b9 100644 (file)
--- a/net/ipv6/seg6_hmac.c
+++ b/net/ipv6/seg6_hmac.c
@@ -399,7 +399,6 @@ int __init seg6_hmac_init(void)
 {
        return seg6_hmac_init_algo();
 }
-EXPORT_SYMBOL(seg6_hmac_init);
 
 int __net_init seg6_hmac_net_init(struct net *net)
 {