As mentioned in a previous commit of this series, using the 'net' structure via 'current' is not recommended for different reasons:
- Inconsistency: getting info from the reader's/writer's netns vs only from the opener's netns.
- current->nsproxy can be NULL in some cases, resulting in an 'Oops' (null-ptr-deref), e.g. when the current task is exiting, as spotted by syzbot [1] using acct(2).
The 'net' structure can be obtained from the table->data using container_of().
Note that table->data could also be used directly, as this is the only member needed from the 'net' structure, but that would increase the size of this fix, to use '*data' everywhere 'net->sctp.probe_interval' is used.
Fixes: d1e462a7a5f3 ("sctp: add probe_interval in sysctl and sock/asoc/transport") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/67769ecb.050a0220.3a8527.003f.GAE@google.com [1] Suggested-by: Al Viro viro@zeniv.linux.org.uk Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org --- net/sctp/sysctl.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c index 18fa4f44e8ec8c86f8415b1251ef8a2979c7f823..8e1e97be4df79f3245e2bbbeb0a75841abc67f58 100644 --- a/net/sctp/sysctl.c +++ b/net/sctp/sysctl.c @@ -569,7 +569,8 @@ static int proc_sctp_do_udp_port(const struct ctl_table *ctl, int write, static int proc_sctp_do_probe_interval(const struct ctl_table *ctl, int write, void *buffer, size_t *lenp, loff_t *ppos) { - struct net *net = current->nsproxy->net_ns; + struct net *net = container_of(ctl->data, struct net, + sctp.probe_interval); struct ctl_table tbl; int ret, new_value;