From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 11AD827703A; Tue, 12 Aug 2025 19:21:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755026473; cv=none; b=XwX/R4nxAA3FxSdzw5nJR9zBq5RfjYMsOgH2RG2ZZ0w9PZ6394eMI5OFRht2Od3mBXgOS9FvMtA6jilXCR/A43uHe5cRzfQByq59qffavPx1h4b2T3kfNmOJtvMvh7WVeRpp5KQxXHUlFUCC7F9Ssin1psFYFpoGSjQ52nGJik0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755026473; c=relaxed/simple; bh=NppkE5M+xsjW7cPlf99EdcJ/+Ia5SSClBx+4dSsiM2Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=czKiA+R6LNw+jDzT1o2OlTtfBk630eQwTQhS7zK4wzFEmC6n5H2yvEsDBKTBtXXyiEUwSmy/jg/wMi3HB6CYBJt/Qz5rRGaZC+DJMqzcxIgIwTm+XBG2oEntYV3xfCsG7TECzQIrXNCFlFDoFSAs3l2waVF1NejigiQxpcF4JCQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=okiZFca8; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="okiZFca8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8BD68C4CEF0; Tue, 12 Aug 2025 19:21:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755026472; bh=NppkE5M+xsjW7cPlf99EdcJ/+Ia5SSClBx+4dSsiM2Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=okiZFca8ZtcbJkuAB3aCeMiq4MMd3+sof0Q+xfh7nk3volADu+QkLtWDSCVr3KHem mB39pAdZ1xJxCWc2gWk7vHB5ZNitn52DWIAx7qDVf3S5cbhXFztPzEl1O4u459JlDh +Vx+yL7WtXDSf/RiqH/RyA+YJTSlWaD9J0hd1kRE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+ccac90e482b2a81d74aa@syzkaller.appspotmail.com, Paul Chaignon , Yonghong Song , Eduard Zingerman , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.15 330/480] bpf: Check flow_dissector ctx accesses are aligned Date: Tue, 12 Aug 2025 19:48:58 +0200 Message-ID: <20250812174411.051500621@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250812174357.281828096@linuxfoundation.org> References: <20250812174357.281828096@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Paul Chaignon [ Upstream commit ead3d7b2b6afa5ee7958620c4329982a7d9c2b78 ] flow_dissector_is_valid_access doesn't check that the context access is aligned. As a consequence, an unaligned access within one of the exposed field is considered valid and later rejected by flow_dissector_convert_ctx_access when we try to convert it. The later rejection is problematic because it's reported as a verifier bug with a kernel warning and doesn't point to the right instruction in verifier logs. Fixes: d58e468b1112 ("flow_dissector: implements flow dissector BPF hook") Reported-by: syzbot+ccac90e482b2a81d74aa@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=ccac90e482b2a81d74aa Signed-off-by: Paul Chaignon Acked-by: Yonghong Song Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/cc1b036be484c99be45eddf48bd78cc6f72839b1.1754039605.git.paul.chaignon@gmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- net/core/filter.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/core/filter.c b/net/core/filter.c index 34f91c3aacb2..ac2cb6eba56e 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -9463,6 +9463,9 @@ static bool flow_dissector_is_valid_access(int off, int size, if (off < 0 || off >= sizeof(struct __sk_buff)) return false; + if (off % size != 0) + return false; + if (type == BPF_WRITE) return false; -- 2.39.5