6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
commit c10377bbc1972d858eaf0ab366a311b39f8ef1b6 upstream.
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, but that would
increase the size of this fix, while 'sctp.ctl_sock' still needs to be
retrieved from 'net' structure.
Fixes: 046c052b475e ("sctp: enable udp tunneling socks")
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/67769ecb.050a0220.3a8527.003f.GAE@xxxxxxxxxx [1]
Suggested-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
Link: https://patch.msgid.link/20250108-net-sysctl-current-nsproxy-v1-7-5df34b2083e8@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/sctp/sysctl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/sctp/sysctl.c
+++ b/net/sctp/sysctl.c
@@ -528,7 +528,7 @@ static int proc_sctp_do_auth(const struc
static int proc_sctp_do_udp_port(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.udp_port);
unsigned int min = *(unsigned int *)ctl->extra1;
unsigned int max = *(unsigned int *)ctl->extra2;
struct ctl_table tbl;
