[PATCH] backports: check if genl pre_doit and post_doit are set

[PATCH] backports: check if genl pre_doit and post_doit are set

[Luca Coelho]

From: Luca Coelho <luciano.coelho@intel.com>

In the pre_doit and post_doit backports, we set the ops to our
backported version, so genetlink itself will always call it.  But then
we don't check if the actual ops are set before calling them, which
causes a call to a NULL pointer.  Fix this by checking if the ops are
actually set before calling them.

Fixes: ff6746638cf1 ("backports: genetlink: update completely")
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
---
 backport/compat/backport-genetlink.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/backport/compat/backport-genetlink.c b/backport/compat/backport-genetlink.c
index cc70cd73d0c0..71bf45adf88d 100644
--- a/backport/compat/backport-genetlink.c
+++ b/backport/compat/backport-genetlink.c
@@ -171,7 +171,7 @@ static int backport_pre_doit(__genl_const struct genl_ops *ops,
 
 	err = nlmsg_validate(info->nlhdr, GENL_HDRLEN + family->hdrsize,
 			     family->maxattr, ops->policy, extack);
-	if (!err)
+	if (!err && family->pre_doit)
 		err = family->pre_doit(ops, skb, info);
 
 #if LINUX_VERSION_IS_LESS(4,12,0)
@@ -205,7 +205,8 @@ static void backport_post_doit(__genl_const struct genl_ops *ops,
 #else
 	if (1)
 #endif
-		family->post_doit(ops, skb, info);
+		if (family->post_doit)
+			family->post_doit(ops, skb, info);
 
 #if LINUX_VERSION_IS_LESS(4,12,0)
 	kfree(__bp_genl_info_userhdr(info));
-- 
2.19.1

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