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 749A3318B9B for ; Mon, 4 May 2026 08:49:16 +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=1777884556; cv=none; b=cVbHzmV9bzhC1Bo7cxnuYlSyczkvLqy8q3vsnDm2g+juBG1T7qERNPuuiferLAGuEDg2ICEWp16reBKf9SxSuNJKCC7AzHAnn+81NPNqroy4Cru+0F1LeL9PnCu++DWtLJcFZM4u55HU0hYeIJqjV0VIA4TpA5dJ8d5mCl99tOY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777884556; c=relaxed/simple; bh=7LI+Y64sqY1/rWUvKKxE2HMQ90cA/ThDjd3c+zEciB4=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=AQkKIvSCZlktvgQ2G7y5eFcexznoAX1w0T1blpLcn5VjSMyfoJLbBp/vCpu57FnSaeGQvwi9kGuyOAlRBBdF+2A88BN8JTGBolx7ePBku1cee6KsPs97Wy7ov7XjFTq/oxroQIieDZQVgLVkw2/jUA+x5eHWib6zZsmh1Hv8NGk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=YNHg6xxu; 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="YNHg6xxu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 028CCC2BCB8; Mon, 4 May 2026 08:49:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1777884556; bh=7LI+Y64sqY1/rWUvKKxE2HMQ90cA/ThDjd3c+zEciB4=; h=Subject:To:Cc:From:Date:From; b=YNHg6xxubDAY2+4L5vMzMgMzJiJW9XWiDHgY6RTC2YAB8yJw5DCYhJFm3ghl//c0o h6gx0KKBOhZLowrG9dyprRzXSH7ObHdl3pT7fsdOx4b2yhQRHxfd75qd7xXSOovj5Y p8OGrGpGYsW4hNuSBUh/qXdzNh0Gz7TTXuoVGIls= Subject: FAILED: patch "[PATCH] erofs: fix unsigned underflow in z_erofs_lz4_handle_overlap()" failed to apply to 6.18-stable tree To: moonafterrain@outlook.com,danisjiang@gmail.com,hsiangkao@linux.alibaba.com Cc: From: Date: Mon, 04 May 2026 10:49:13 +0200 Message-ID: <2026050413-commute-discourse-5f47@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y git checkout FETCH_HEAD git cherry-pick -x 21e161de2dc660b1bb70ef5b156ab8e6e1cca3ab # git commit -s git send-email --to '' --in-reply-to '2026050413-commute-discourse-5f47@gregkh' --subject-prefix 'PATCH 6.18.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 21e161de2dc660b1bb70ef5b156ab8e6e1cca3ab Mon Sep 17 00:00:00 2001 From: Junrui Luo Date: Thu, 9 Apr 2026 21:59:39 +0800 Subject: [PATCH] erofs: fix unsigned underflow in z_erofs_lz4_handle_overlap() Some crafted images can have illegal (!partial_decoding && m_llen < m_plen) extents, and the LZ4 inplace decompression path can be wrongly hit, but it cannot handle (outpages < inpages) properly: "outpages - inpages" wraps to a large value and the subsequent rq->out[] access reads past the decompressed_pages array. However, such crafted cases can correctly result in a corruption report in the normal LZ4 non-inplace path. Let's add an additional check to fix this for backporting. Reproducible image (base64-encoded gzipped blob): H4sIAJGR12kCA+3SPUoDQRgG4MkmkkZk8QRbRFIIi9hbpEjrHQI5ghfwCN5BLCzTGtLbBI+g dilSJo1CnIm7GEXFxhT6PDDwfrs73/ywIQD/1ePD4r7Ou6ETsrq4mu7XcWfj++Pb58nJU/9i PNtbjhan04/9GtX4qVYc814WDqt6FaX5s+ZwXXeq52lndT6IuVvlblytLMvh4Gzwaf90nsvz 2DF/21+20T/ldgp5s1jXRaN4t/8izsy/OUB6e/Qa79r+JwAAAAAAAL52vQVuGQAAAP6+my1w ywAAAAAAAADwu14ATsEYtgBQAAA= $ mount -t erofs -o cache_strategy=disabled foo.erofs /mnt $ dd if=/mnt/data of=/dev/null bs=4096 count=1 Fixes: 598162d05080 ("erofs: support decompress big pcluster for lz4 backend") Reported-by: Yuhao Jiang Cc: stable@vger.kernel.org Signed-off-by: Junrui Luo Reviewed-by: Gao Xiang Signed-off-by: Gao Xiang diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c index 3c54e95964c9..2b065f8c3f71 100644 --- a/fs/erofs/decompressor.c +++ b/fs/erofs/decompressor.c @@ -145,6 +145,7 @@ static void *z_erofs_lz4_handle_overlap(const struct z_erofs_decompress_req *rq, oend = rq->pageofs_out + rq->outputsize; omargin = PAGE_ALIGN(oend) - oend; if (!rq->partial_decoding && may_inplace && + rq->outpages >= rq->inpages && omargin >= LZ4_DECOMPRESS_INPLACE_MARGIN(rq->inputsize)) { for (i = 0; i < rq->inpages; ++i) if (rq->out[rq->outpages - rq->inpages + i] !=