From patchwork Wed Aug 7 19:51:23 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 13756664 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 548FF13F42D; Wed, 7 Aug 2024 19:51:28 +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=1723060289; cv=none; b=nTQBfAed+4s5UWxo4stIgfNWJ2jBoZxvgPlDQseU7erMv1jt2RQDl3FCZ17kWthzkGgaWDf9BUcoAeBGOfjiswEdHKuFslt8GSdfmRYucdM/Hb0goSEMlcHP+PDYF20c0oElRRYOFgQfiGFdGEY8fTRMncrufCsfdgojcOT9Sdk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723060289; c=relaxed/simple; bh=SvqeU/ZIJL4InXKZ4IE/gkXwgJ0pFR9Ce/8L1Ah0vsQ=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=t02S6S2eCf0k3ylHTi49UTyyRi1u0LdszVTufyIK/q7rje6bDEwXFRz29dtb3ZPTcb1yg6A7wAgHoCi5gRgyNi+L/HJWIxR98T5YUMJ39vgoXoIYX9CjucCdFzkQT+a2yPQKPBJvUdVVmzcreOYeLMYNaNgeAVdOvtP6e1+7xUg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=f2Zv5nWy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="f2Zv5nWy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B1499C32781; Wed, 7 Aug 2024 19:51:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1723060288; bh=SvqeU/ZIJL4InXKZ4IE/gkXwgJ0pFR9Ce/8L1Ah0vsQ=; h=From:To:Cc:Subject:Date:From; b=f2Zv5nWyAL78JMALjEvnyPwQPdTRf9kMWSjuMAYiDlgp9dt+1Ig1gnZQNmwYKXe0F 0oqFWF+shI8uRVvf1w8LS9ilw0dlV56mHBNDsYu0+TurLhf8wuUcVCNtEvGX8BkTGG 9hBP2N+srYnnCZ6mh6kAb6mTMh8R+9H+qoCQipQf+ErAaQS2asDT+k9/7hbT3iNels +y/wf5ZQ77Fs2Bzri4wX2PtRKGs6YFo/lz3ZRQgvTshKxxezDWDYFQX85GG72hT8Z1 CMZyVCmKIqeUfyQX3yK7CCw08VSqGpQN6VdVoVG1mIDsKl8PuRmg4jUCmCdtQ6XM9q IhmzUe++1V8Vg== From: Kees Cook To: Palmer Dabbelt Cc: Kees Cook , Stefan O'Rear , Alexandre Ghiti , Greg Ungerer , Damien Le Moal , Alexander Viro , Christian Brauner , Jan Kara , Eric Biederman , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Damien Le Moal , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v2] binfmt_flat: Fix corruption when not offsetting data start Date: Wed, 7 Aug 2024 12:51:23 -0700 Message-Id: <20240807195119.it.782-kees@kernel.org> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2234; i=kees@kernel.org; h=from:subject:message-id; bh=SvqeU/ZIJL4InXKZ4IE/gkXwgJ0pFR9Ce/8L1Ah0vsQ=; b=owGbwMvMwCVmps19z/KJym7G02pJDGmbL1hNX7o1ZHXuhwPhrQXex+8t+tBiLXdh59PcrYLOx zRumG+d0lHKwiDGxSArpsgSZOce5+Lxtj3cfa4izBxWJpAhDFycAjARbmtGhlk2q14+YHWddP+E zcXEValhnC5FBgoXfz9/bfQ4c0rM1ApGhpchtm0T1K35dYO2mXMF/d7+YFVbadhndv3tiS9eBO/ fwwAA X-Developer-Key: i=kees@kernel.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Commit 04d82a6d0881 ("binfmt_flat: allow not offsetting data start") introduced a RISC-V specific variant of the FLAT format which does not allocate any space for the (obsolete) array of shared library pointers. However, it did not disable the code which initializes the array, resulting in the corruption of sizeof(long) bytes before the DATA segment, generally the end of the TEXT segment. Introduce MAX_SHARED_LIBS_UPDATE which depends on the state of CONFIG_BINFMT_FLAT_NO_DATA_START_OFFSET to guard the initialization of the shared library pointer region so that it will only be initialized if space is reserved for it. Fixes: 04d82a6d0881 ("binfmt_flat: allow not offsetting data start") Co-developed-by: Stefan O'Rear Signed-off-by: Stefan O'Rear Signed-off-by: Kees Cook Reviewed-by: Damien Le Moal Acked-by: Greg Ungerer --- v2: update based on v1 feedback v1: https://lore.kernel.org/linux-mm/20240326032037.2478816-1-sorear@fastmail.com/ Cc: Palmer Dabbelt Cc: Alexandre Ghiti Cc: Greg Ungerer Cc: Damien Le Moal Cc: Alexander Viro Cc: Christian Brauner Cc: Jan Kara Cc: Eric Biederman Cc: linux-fsdevel@vger.kernel.org Cc: linux-mm@kvack.org --- fs/binfmt_flat.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c index c26545d71d39..cd6d5bbb4b9d 100644 --- a/fs/binfmt_flat.c +++ b/fs/binfmt_flat.c @@ -72,8 +72,10 @@ #ifdef CONFIG_BINFMT_FLAT_NO_DATA_START_OFFSET #define DATA_START_OFFSET_WORDS (0) +#define MAX_SHARED_LIBS_UPDATE (0) #else #define DATA_START_OFFSET_WORDS (MAX_SHARED_LIBS) +#define MAX_SHARED_LIBS_UPDATE (MAX_SHARED_LIBS) #endif struct lib_info { @@ -880,7 +882,7 @@ static int load_flat_binary(struct linux_binprm *bprm) return res; /* Update data segment pointers for all libraries */ - for (i = 0; i < MAX_SHARED_LIBS; i++) { + for (i = 0; i < MAX_SHARED_LIBS_UPDATE; i++) { if (!libinfo.lib_list[i].loaded) continue; for (j = 0; j < MAX_SHARED_LIBS; j++) {