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 3D01F1A9F89; Tue, 12 Aug 2025 18:01:20 +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=1755021681; cv=none; b=ofQXn1GgUqU+uveJqiMuueMAXMXtlmJ+hzbacGqxvGBCvx0vaCbTefzeKa4HGeJ5eBNNQY14C+gGicjeMzH+TXmeF0rtz8ybarsxL6zm0cYmmD91q8/rJpbFU5Wm0KG3ISTpkmw0qwbOc6l5vuZdcYw7M148bw5d2Zmgxt/EMfU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755021681; c=relaxed/simple; bh=IOoeeB25I7jmrLsE2Jeo/IhxDy7siKV6mKwrLXmpSDA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CrNG//Yyu8mK6gWGZr3yO3dVZZeLAfMznwztR+Nv9J2cKdTK+r5hMTsLgF6cw5HOa7+ysIw7c7j4sBKVutLH95rV5SGAWUNpZphQVBAqQu7Vqr1hl9i4Or7ghw4q8veUoKI1Yog/gOciAdOT4LGV/5637Xts/drhQexYunTR0XQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=MJLAJNVU; 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="MJLAJNVU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6B38BC4CEF0; Tue, 12 Aug 2025 18:01:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755021680; bh=IOoeeB25I7jmrLsE2Jeo/IhxDy7siKV6mKwrLXmpSDA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MJLAJNVUZ7BljLsfRFvSI/zztn1XXudFBQvNqeFRPe8JGI0JvvI+B2Tkx+64kCxY1 ylsGr+Br0drUmaWVTtRUdGu3U9+jpP6vFEaeIw/y+x9J9/GE9ZEBXtcUaiqH+hlXgF +AMEk3whBn5q3IzMI+LKOTtETQZoXjo+J3NX9eck= 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 6.6 160/262] bpf: Check flow_dissector ctx accesses are aligned Date: Tue, 12 Aug 2025 19:29:08 +0200 Message-ID: <20250812172959.913403187@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250812172952.959106058@linuxfoundation.org> References: <20250812172952.959106058@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-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 3e10b4c8338f..7afb7658c388 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -9330,6 +9330,9 @@ 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