Commit c10377bb authored by Matthieu Baerts (NGI0)'s avatar Matthieu Baerts (NGI0) Committed by Jakub Kicinski
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sctp: sysctl: udp_port: avoid using current->nsproxy 

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: 046c052b ("sctp: enable udp tunneling socks")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/67769ecb.050a0220.3a8527.003f.GAE@google.com

 [1]
Suggested-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarMatthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20250108-net-sysctl-current-nsproxy-v1-7-5df34b2083e8@kernel.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 15649fd5

net/sctp/sysctl.c

+1 −1
Original line number Diff line number Diff line
@@ -528,7 +528,7 @@ static int proc_sctp_do_auth(const struct ctl_table *ctl, int write, 
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;