From 96ca579a1ecc943b75beba58bebb0356f6cc4b51 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Mon, 9 Oct 2017 11:36:52 -0700 Subject: waitid(): Add missing access_ok() checks Adds missing access_ok() checks. CVE-2017-5123 Reported-by: Chris Salls Signed-off-by: Kees Cook Acked-by: Al Viro Fixes: 4c48abe91be0 ("waitid(): switch copyout of siginfo to unsafe_put_user()") Cc: stable@kernel.org # 4.13 Signed-off-by: Linus Torvalds --- kernel/exit.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'kernel/exit.c') diff --git a/kernel/exit.c b/kernel/exit.c index f2cd53e92147..cf28528842bc 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1610,6 +1610,9 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, if (!infop) return err; + if (!access_ok(VERIFY_WRITE, infop, sizeof(*infop))) + goto Efault; + user_access_begin(); unsafe_put_user(signo, &infop->si_signo, Efault); unsafe_put_user(0, &infop->si_errno, Efault); @@ -1735,6 +1738,9 @@ COMPAT_SYSCALL_DEFINE5(waitid, if (!infop) return err; + if (!access_ok(VERIFY_WRITE, infop, sizeof(*infop))) + goto Efault; + user_access_begin(); unsafe_put_user(signo, &infop->si_signo, Efault); unsafe_put_user(0, &infop->si_errno, Efault); -- cgit v1.2.2 From 1c9fec470b81ca5e89391c20a11ead31a1e9314b Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 20 Oct 2017 07:36:05 -0700 Subject: waitid(): Avoid unbalanced user_access_end() on access_ok() error As pointed out by Linus and David, the earlier waitid() fix resulted in a (currently harmless) unbalanced user_access_end() call. This fixes it to just directly return EFAULT on access_ok() failure. Fixes: 96ca579a1ecc ("waitid(): Add missing access_ok() checks") Acked-by: David Daney Cc: Al Viro Signed-off-by: Kees Cook Signed-off-by: Linus Torvalds --- kernel/exit.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/exit.c') diff --git a/kernel/exit.c b/kernel/exit.c index cf28528842bc..f6cad39f35df 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1611,7 +1611,7 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, return err; if (!access_ok(VERIFY_WRITE, infop, sizeof(*infop))) - goto Efault; + return -EFAULT; user_access_begin(); unsafe_put_user(signo, &infop->si_signo, Efault); @@ -1739,7 +1739,7 @@ COMPAT_SYSCALL_DEFINE5(waitid, return err; if (!access_ok(VERIFY_WRITE, infop, sizeof(*infop))) - goto Efault; + return -EFAULT; user_access_begin(); unsafe_put_user(signo, &infop->si_signo, Efault); -- cgit v1.2.2