linux-kernel - [PATCH] fork: fail on non-zero higher 32 bits of args.exit

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 10 Sep 2019 12:57:11 +0100
From:   Eugene Syromiatnikov <esyr@...hat.com>
To:     linux-kernel@...r.kernel.org,
        Christian Brauner <christian@...uner.io>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        "Dmitry V. Levin" <ldv@...linux.org>,
        Eric Biederman <ebiederm@...ssion.com>,
        Oleg Nesterov <oleg@...hat.com>
Subject: [PATCH] fork: fail on non-zero higher 32 bits of args.exit_signal

Previously, higher 32 bits of exit_signal fields were lost when
copied to the kernel args structure (that uses int as a type for the
respective field).  Fail with EINVAL if these are set as it looks like
there's no sane reason to accept them.

* kernel/fork.c (copy_clone_args_from_user): Fail with -EINVAL if
args.exit_signal converted to unsigned int is not equal to the original
value.

Signed-off-by: Eugene Syromiatnikov <esyr@...hat.com>
---
 kernel/fork.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/fork.c b/kernel/fork.c
index 2852d0e..fcbc4d5 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2562,6 +2562,9 @@ noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
 	if (copy_from_user(&args, uargs, size))
 		return -EFAULT;
 
+	if (unlikely(((unsigned int)args.exit_signal) != args.exit_signal))
+		return -EINVAL;
+
 	*kargs = (struct kernel_clone_args){
 		.flags		= args.flags,
 		.pidfd		= u64_to_user_ptr(args.pidfd),
-- 
2.1.4