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From: Loris Reiff <loris.reiff@liblor.ch>
To: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
	andrii@kernel.org, kafai@fb.com, songliubraving@fb.com,
	yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org,
	sdf@google.com, Loris Reiff <loris.reiff@liblor.ch>
Subject: [PATCH 2/2] bpf: cgroup: Fix problematic bounds check
Date: Fri, 22 Jan 2021 17:42:32 +0100	[thread overview]
Message-ID: <20210122164232.61770-2-loris.reiff@liblor.ch> (raw)
In-Reply-To: <20210122164232.61770-1-loris.reiff@liblor.ch>

Since ctx.optlen is signed, a larger value than max_value could be
passed, as it is later on used as unsigned, which causes a WARN_ON_ONCE
in the copy_to_user.

Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks")
Signed-off-by: Loris Reiff <loris.reiff@liblor.ch>
---
 kernel/bpf/cgroup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 6ec8f02f4..6aa9e10c6 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -1464,7 +1464,7 @@ int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
 		goto out;
 	}
 
-	if (ctx.optlen > max_optlen) {
+	if (ctx.optlen > max_optlen || ctx.optlen < 0) {
 		ret = -EFAULT;
 		goto out;
 	}
-- 
2.29.2


  reply	other threads:[~2021-01-22 16:51 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-22 16:42 [PATCH 1/2] bpf: cgroup: Fix optlen WARN_ON_ONCE toctou Loris Reiff
2021-01-22 16:42 ` Loris Reiff [this message]
2021-01-22 17:04   ` [PATCH 2/2] bpf: cgroup: Fix problematic bounds check Stanislav Fomichev
2021-01-22 17:10     ` Loris Reiff
2021-01-22 17:04 ` [PATCH 1/2] bpf: cgroup: Fix optlen WARN_ON_ONCE toctou Stanislav Fomichev
2021-01-22 22:20 ` patchwork-bot+netdevbpf

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