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 4D25128314A; Tue, 26 Aug 2025 13:44:44 +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=1756215885; cv=none; b=ALYUfbunyziZFfEBXqUwPp72l2tUezzDHF8F/L9aenUc6YJUZECDyY1bLtTr0P0tv6I8O1Af1wM+ASHNMpw0NrE/bhl3ZXqtZlYnkatT9XGxY+ZQqERyrHeF2bFtZvpYCYVrInLs8kAlabCdYscxR4wai8dYdW3eH6u4507wyF0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756215885; c=relaxed/simple; bh=Zq6qgLoauGsh/zUxLi2QThKXJLiMbHnkHD+qyOwqxSA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sIH+lfpXpcemAWMrgpUnu1gGZPdtmMhfXE9WDptA4WnOOW1hqw+bLIHZS2LVCBlGPTFy2xSNWf1KjVPSpuOGHmeUb68zY867LkDuIoeAByOct/C5mLH1i8iwY24HlTqsV1Sebg5Ih7rXC3I2cfy1DDrrUI/IwPcSCW16jQWxHyw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=NdnW2OZ/; 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="NdnW2OZ/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 898A2C4CEF1; Tue, 26 Aug 2025 13:44:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1756215883; bh=Zq6qgLoauGsh/zUxLi2QThKXJLiMbHnkHD+qyOwqxSA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NdnW2OZ/0Ucgrg5yGXKTW7Q4m3AcnyNVFNUzQ6ESYSDl1aDylUSM1WJA30/MJBe2l Unv3GUDqkWsSPVQ0zJbvsE4whGecRk2AbKNMG/L3fGVzQZs4e48nMEq0U6VO1346GK vnX1Bm1h29MkPLU7n00bnK+5SFwS1FdjOUGLrTDA= 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 5.15 203/644] bpf: Check flow_dissector ctx accesses are aligned Date: Tue, 26 Aug 2025 13:04:54 +0200 Message-ID: <20250826110951.467259230@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250826110946.507083938@linuxfoundation.org> References: <20250826110946.507083938@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 5.15-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 169d9ba4e7a0..f346f19cf468 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -8764,6 +8764,9 @@ 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