From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 E118D3BE643; Sat, 12 Sep 2026 12:22:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789215739; cv=none; b=kkhtnHmlGS41I0sTi2KxTh3RqoHl1Ha7DhFhPMpXYp/E81QwLtseEs4/Xoas98SVm99c16nJkbNgRLWARI6V153wLf32pbLXlLQpEeFRpyYjjy+mn5PJNHn0NdfnHUER2W6cXwtSsZCoktQOR/xOgZTtoyBVa0A0UHLz+6TXn5E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789215739; c=relaxed/simple; bh=k9Q6Tyeqlv85a+31m4sBnXW1QsT885V9GM5aiOhOSQM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BtEJin/TDmFTDGLOSM/aqRSuwk6X6jEvQJ7Q5JR/2Y/YbW+INXaHuUVg6YiguRhETLs93b9Q7VTssQV3DiOY+Rb42mx0FI1Bu3VABK7JOVffl98fe+MaKfuxwCH4AJrXbqiyEj0KxR05bikqfmWPqMEZD6MO+/6hQlQJTlE2+9Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=XvwPc1vL; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="XvwPc1vL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2FC891F000FF; Sat, 12 Sep 2026 12:22:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789215737; bh=aDR7ZTvdGyhDKtqrq6Q2XvZPLOrhOrJ7clB2B2G2a2E=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=XvwPc1vLX/50hTEsqNPBhoqEjvlMEa+bV8oQ+6cQEAxrnx41OX4ZY2XiykFuqJzN7 QKcjoYPJyA6SNOskX7ajxSypzxgwQv8vL/xXSXzOnGGnxdZeEe81LhI8l1nurA3wD/ sRFEbVsl00NwLpyuprCazXaSWR6DPvC5RLYHLCPY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, zhouminqiang , Zhihao Cheng , Miquel Raynal , Sasha Levin Subject: [PATCH 6.12 0592/1376] mtd: part: reject MTDPART_OFS_RETAIN in mtd_add_partition() Date: Sat, 12 Sep 2026 08:50:18 +0200 Message-ID: <20260912065620.728592052@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065607.535295758@linuxfoundation.org> References: <20260912065607.535295758@linuxfoundation.org> User-Agent: quilt/0.69 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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: zhouminqiang [ Upstream commit b759d5bb6265419344ee9729fd0dc07ad85719d8 ] mtd_add_partition() does not reject the special offset value MTDPART_OFS_RETAIN (-3), which leads to a WARN_ON in add_mtd_device() when called through the BLKPG ioctl on NAND devices. The RETAIN value depends on cur_offset being the end of the previous partition, but in the dynamic partition path cur_offset equals the offset argument itself, causing undefined behavior. Commit 5daa7b21496a ("mtd: prepare partition add and del functions for ioctl requests") introduced mtd_add_partition() and correctly rejected MTDPART_OFS_APPEND (-1) and MTDPART_OFS_NXTBLK (-2), since those special offsets rely on cur_offset tracking the previous partition's end. However, commit 1a31368bf92e ("mtd: add a flags for partitions which should just leave smth. after them") later added MTDPART_OFS_RETAIN (-3) for the static partition table path without updating mtd_add_partition() to also reject this value. With offset=-3 passed via BLKPG, the RETAIN size calculation in allocate_partition() underflows (parent_size - 0xFFFFFFFFFFFFFFFD = parent_size + 3). If the underflow result does not appear to leave enough space, allocate_partition() jumps to out_register via goto, skipping erasesize initialization. This results in erasesize=0, which triggers: WARN_ON((!mtd->erasesize || !master->_erase) && !(mtd->flags & MTD_NO_ERASE)) in add_mtd_device(). If the underflow result appears to leave enough space, a bogus partition size is calculated, but the "out of reach" sanity check catches the invalid offset and creates a disabled empty partition (offset=0, size=0) instead of returning an error. Fix this by adding MTDPART_OFS_RETAIN to the rejection list in mtd_add_partition(), consistent with the existing handling of APPEND and NXTBLK. Fixes: 1a31368bf92e ("mtd: add a flags for partitions which should just leave smth. after them") Signed-off-by: zhouminqiang Reviewed-by: Zhihao Cheng Signed-off-by: Miquel Raynal Signed-off-by: Sasha Levin --- drivers/mtd/mtdpart.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c index 208532d86cc93..c3ba57215c860 100644 --- a/drivers/mtd/mtdpart.c +++ b/drivers/mtd/mtdpart.c @@ -254,7 +254,8 @@ int mtd_add_partition(struct mtd_info *parent, const char *name, /* the direct offset is expected */ if (offset == MTDPART_OFS_APPEND || - offset == MTDPART_OFS_NXTBLK) + offset == MTDPART_OFS_NXTBLK || + offset == MTDPART_OFS_RETAIN) return -EINVAL; if (length == MTDPART_SIZ_FULL) -- 2.53.0