From: Matthieu Baerts (NGI0) Date: Wed, 8 Jan 2025 15:34:31 +0000 (+0100) Subject: mptcp: sysctl: blackhole timeout: avoid using current->nsproxy X-Git-Tag: v6.13-rc7~29^2~1^2~6 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=92cf7a51bdae24a32c592adcdd59a773ae149289;p=thirdparty%2Flinux.git mptcp: sysctl: blackhole timeout: avoid using current->nsproxy As mentioned in the previous commit, 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 'pernet' structure can be obtained from the table->data using container_of(). Fixes: 27069e7cb3d1 ("mptcp: disable active MPTCP in case of blackhole") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/67769ecb.050a0220.3a8527.003f.GAE@google.com [1] Suggested-by: Al Viro Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250108-net-sysctl-current-nsproxy-v1-3-5df34b2083e8@kernel.org Signed-off-by: Jakub Kicinski --- diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c index 81c30aa02196d..b0dd008e2114b 100644 --- a/net/mptcp/ctrl.c +++ b/net/mptcp/ctrl.c @@ -160,7 +160,9 @@ static int proc_blackhole_detect_timeout(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { - struct mptcp_pernet *pernet = mptcp_get_pernet(current->nsproxy->net_ns); + struct mptcp_pernet *pernet = container_of(table->data, + struct mptcp_pernet, + blackhole_timeout); int ret; ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);