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authorMatthieu Baerts (NGI0) <matttbe@kernel.org>2025-01-08 16:34:33 +0100
committerJakub Kicinski <kuba@kernel.org>2025-01-09 17:53:34 +0100
commit9fc17b76fc70763780aa78b38fcf4742384044a5 (patch)
tree425397f829a534e642559c259f190c1417038f42
parentsctp: sysctl: cookie_hmac_alg: avoid using current->nsproxy (diff)
downloadlinux-9fc17b76fc70763780aa78b38fcf4742384044a5.tar.xz
linux-9fc17b76fc70763780aa78b38fcf4742384044a5.zip
sctp: sysctl: rto_min/max: 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, 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.rto_min/max' is used. Fixes: 4f3fdf3bc59c ("sctp: add check rto_min and rto_max in sysctl") 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> Link: https://patch.msgid.link/20250108-net-sysctl-current-nsproxy-v1-5-5df34b2083e8@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
-rw-r--r--net/sctp/sysctl.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c
index 9848d19630a4..a5285815264d 100644
--- a/net/sctp/sysctl.c
+++ b/net/sctp/sysctl.c
@@ -433,7 +433,7 @@ static int proc_sctp_do_hmac_alg(const struct ctl_table *ctl, int write,
static int proc_sctp_do_rto_min(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.rto_min);
unsigned int min = *(unsigned int *) ctl->extra1;
unsigned int max = *(unsigned int *) ctl->extra2;
struct ctl_table tbl;
@@ -461,7 +461,7 @@ static int proc_sctp_do_rto_min(const struct ctl_table *ctl, int write,
static int proc_sctp_do_rto_max(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.rto_max);
unsigned int min = *(unsigned int *) ctl->extra1;
unsigned int max = *(unsigned int *) ctl->extra2;
struct ctl_table tbl;