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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Hsuan-Chi Kuo <hsuanchikuo@gmail.com>,
        Wiktor Garbacz <wiktorg@google.com>,
        Kees Cook <keescook@chromium.org>
Subject: [PATCH 5.13 022/151] seccomp: Fix setting loaded filter count during TSYNC
Date:   Mon, 16 Aug 2021 15:00:52 +0200
Message-Id: <20210816125444.801772013@linuxfoundation.org>
In-Reply-To: <20210816125444.082226187@linuxfoundation.org>
References: <20210816125444.082226187@linuxfoundation.org>
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From: Hsuan-Chi Kuo <hsuanchikuo@gmail.com>

commit b4d8a58f8dcfcc890f296696cadb76e77be44b5f upstream.

The desired behavior is to set the caller's filter count to thread's.
This value is reported via /proc, so this fixes the inaccurate count
exposed to userspace; it is not used for reference counting, etc.

Signed-off-by: Hsuan-Chi Kuo <hsuanchikuo@gmail.com>
Link: https://lore.kernel.org/r/20210304233708.420597-1-hsuanchikuo@gmail.com
Co-developed-by: Wiktor Garbacz <wiktorg@google.com>
Signed-off-by: Wiktor Garbacz <wiktorg@google.com>
Link: https://lore.kernel.org/lkml/20210810125158.329849-1-wiktorg@google.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Fixes: c818c03b661c ("seccomp: Report number of loaded filters in /proc/$pid/status")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 kernel/seccomp.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -602,7 +602,7 @@ static inline void seccomp_sync_threads(
 		smp_store_release(&thread->seccomp.filter,
 				  caller->seccomp.filter);
 		atomic_set(&thread->seccomp.filter_count,
-			   atomic_read(&thread->seccomp.filter_count));
+			   atomic_read(&caller->seccomp.filter_count));
 
 		/*
 		 * Don't let an unprivileged task work around