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netfilter: nfnetlink: reset nlh pointer during batch replay 

During a batch replay, the nlh pointer is not reset until the parsing of
the commands. Since commit bf2ac490d2 ("netfilter: nfnetlink: Handle
ACK flags for batch messages") that is problematic as the condition to
add an ACK for batch begin will evaluate to true even if NLM_F_ACK
wasn't used for batch begin message.

If there is an error during the command processing, netlink is sending
an ACK despite that. This misleads userspace tools which think that the
return code was 0. Reset the nlh pointer to the original one when a
replay is triggered.

Fixes: bf2ac490d2 ("netfilter: nfnetlink: Handle ACK flags for batch messages")
Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Signed-off-by: Florian Westphal <fw@strlen.de>
pull/1354/merge
Fernando Fernandez Mancera 2025-09-19 14:40:43 +02:00 committed by Florian Westphal
parent 134121bfd9
commit 09efbac953
1 changed files with 2 additions and 0 deletions
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2
net/netfilter/nfnetlink.c
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@ -376,6 +376,7 @@ static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
const struct nfnetlink_subsystem *ss;
const struct nfnl_callback *nc;
struct netlink_ext_ack extack;
struct nlmsghdr *onlh = nlh;
LIST_HEAD(err_list);
u32 status;
int err;
@ -386,6 +387,7 @@ replay:
status = 0;
replay_abort:
skb = netlink_skb_clone(oskb, GFP_KERNEL);
nlh = onlh;
if (!skb)
return netlink_ack(oskb, nlh, -ENOMEM, NULL);