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 950EC33B6CC; Tue, 12 May 2026 18:01:52 +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=1778608912; cv=none; b=ez4QWKHQwx0cTJSHcE9a3PdGEU/TgPmxBWMAeP/Za61Gkd77cWq2vXxjYdMJcnJJYdsmv8bMYgMUf4cM+B5RhQgtyFe2f8f0Nwyku88W5TS/kNo5GIKlzcQbOcemiR1+4Y7FbpgxP0Jn6qc75FX2aDq82dyNb0MwxvFEztrfwos= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778608912; c=relaxed/simple; bh=VTAagBqcSDMS1Roolhsuq0DwJLIsYS+uEo+gSIy14i4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Fb1ACzfPy3dazdEk6HAc5HnWl+KGogBsztPteoNC1Tn3CuJLGH/VCdaIAgN5BqCsXaqi6ItyOCk67NoeLie2BscsCAOu/ozS/gJtwXlY/4oNTchgtkBnLckfX/+71+3AjAB8KCnHnuKP3zlDZXjXsANoC3wk8sIjb1f6Xmj2PDA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cTkIZ9hH; 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="cTkIZ9hH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2C328C2BCB0; Tue, 12 May 2026 18:01:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778608912; bh=VTAagBqcSDMS1Roolhsuq0DwJLIsYS+uEo+gSIy14i4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cTkIZ9hHcl5gPwH8spjstoqT3OFWF5es8k25u+AF0oEmv2NTcOOAzAvIZC/nPtp1l SV9pDHGWzTDRLGRKBrAKE8c1iVWD27JqnHeyzmYHlixa6cy2zo8/5a9AVgnG9xZb74 mmm3XR21HVBKMDGGPehjhP/HALv5vK454lti9mwQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yuhao Jiang , Junrui Luo , Gao Xiang , Sasha Levin Subject: [PATCH 6.18 264/270] erofs: fix unsigned underflow in z_erofs_lz4_handle_overlap() Date: Tue, 12 May 2026 19:41:05 +0200 Message-ID: <20260512173944.007812675@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260512173938.452574370@linuxfoundation.org> References: <20260512173938.452574370@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Junrui Luo [ Upstream commit 21e161de2dc660b1bb70ef5b156ab8e6e1cca3ab ] 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 Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/erofs/decompressor.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/erofs/decompressor.c +++ b/fs/erofs/decompressor.c @@ -142,6 +142,7 @@ static void *z_erofs_lz4_handle_overlap( 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] !=