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 B5183CA6F; Sat, 12 Sep 2026 14:32:17 +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=1789223538; cv=none; b=LkeacwDs+Pqw0nSBWHFTnuVGmO/+b8J1eC4Bz+THQ49FrdoZp9NFph8HQIel3252VXjCJyZ4r+hSyKKSkW+EJJT9jMqx/QXxr+mmV0tN1rVt8mK63+aYbBvquqY56xa16CUIYuUODtss7GB9e+/IBvu1HaEoDK0eEATsLSrBGNg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789223538; c=relaxed/simple; bh=it3hWNPFIlvQGQtrptCVFEj0ZqHROOQee+Fb87o1dRw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=APNngiIb/DgDc9BV+o598BaJfHdsEuooKaqc5+oIOKRrrwrEyh0AN6tRhbXmPn/w7sxpJ03i0fN7pdIPvJBmNDRHWvIwg+oxW2xMpQsf1YBf3ac1MGjA8i4hlSLdffF3JMXO2Sxop2RoUuxjMM21OiRDxatvPbKkTRIkPRYz1ts= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=GFyvDhx2; 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="GFyvDhx2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6E7CE1F000FF; Sat, 12 Sep 2026 14:32:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789223537; bh=aNxL4F7WS3ScEH3rSQmHBfvIu5RtUEqNx1NrnNiQGJs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=GFyvDhx2Es1s5iI1VLFkY58vIV/Jo83xfdFKoDV154YgDcvVhvyWgGza01XRMeCiO ds5DP3X9eq3FXft7M71N0xveIjLF1T4bBHhmFg5yDbZIWI5TUghB//nWA+vqEyQ2BS 08vy2jEqUyGyOj7Jdje2tBHMS0olzAXGKS6RbDcg= 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 6.6 0808/1424] mtd: part: reject MTDPART_OFS_RETAIN in mtd_add_partition() Date: Sat, 12 Sep 2026 08:54:00 +0200 Message-ID: <20260912065625.387269287@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065607.279695368@linuxfoundation.org> References: <20260912065607.279695368@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 6.6-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 23483db8f30c9..5c809a12aff5d 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