6.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
[ Upstream commit 718e6b51298e0f254baca0d40ab52a00e004e014 ]
Heiko Carstens reported that SCM_PIDFD does not work with MSG_CMSG_COMPAT
because scm_pidfd_recv() always checks msg_controllen against sizeof(struct
cmsghdr).
We need to use sizeof(struct compat_cmsghdr) for the compat case.
Fixes: 5e2ff6704a27 ("scm: add SO_PASSPIDFD and SCM_PIDFD")
Reported-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Closes: https://lore.kernel.org/netdev/20230901200517.8742-A-hca@xxxxxxxxxxxxx/
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Tested-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Reviewed-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@xxxxxxxxxxxxx>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@xxxxxxxxxxxxxxx>
Acked-by: Christian Brauner <brauner@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
include/net/scm.h | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/include/net/scm.h b/include/net/scm.h
index c5bcdf65f55c9..e8c76b4be2fe7 100644
--- a/include/net/scm.h
+++ b/include/net/scm.h
@@ -9,6 +9,7 @@
#include <linux/pid.h>
#include <linux/nsproxy.h>
#include <linux/sched/signal.h>
+#include <net/compat.h>
/* Well, we should have at least one descriptor open
* to accept passed FDs 8)
@@ -123,14 +124,17 @@ static inline bool scm_has_secdata(struct socket *sock)
static __inline__ void scm_pidfd_recv(struct msghdr *msg, struct scm_cookie *scm)
{
struct file *pidfd_file = NULL;
- int pidfd;
+ int len, pidfd;
- /*
- * put_cmsg() doesn't return an error if CMSG is truncated,
+ /* put_cmsg() doesn't return an error if CMSG is truncated,
* that's why we need to opencode these checks here.
*/
- if ((msg->msg_controllen <= sizeof(struct cmsghdr)) ||
- (msg->msg_controllen - sizeof(struct cmsghdr)) < sizeof(int)) {
+ if (msg->msg_flags & MSG_CMSG_COMPAT)
+ len = sizeof(struct compat_cmsghdr) + sizeof(int);
+ else
+ len = sizeof(struct cmsghdr) + sizeof(int);
+
+ if (msg->msg_controllen < len) {
msg->msg_flags |= MSG_CTRUNC;
return;
}
--
2.40.1
