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 D066F282F38 for ; Sat, 9 May 2026 03:22:32 +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=1778296952; cv=none; b=eS7kfoYAfCF54xvNNar10AyCBwYcK1crFz9pwo4hAGhzAjRSr2Z3s4ti/oufEdYxwF5Dc5F8NGq9hQSdQTHoQKmGw3XhoWtbTx3RB8GkbtJEbUWeT26GgNbT4lWbbAs48k9cxOLQbO0Gvbg5YTaPdPpRUZwoDG3a1fXv4WCRJec= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778296952; c=relaxed/simple; bh=JFEbBbQppXOY0TFs2/qsQyNSm+VEc8Wki5HFbwZxZZI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iTd1vXJY3ErCevcGKHwhClrNbEa/FH3Q7JjNoAdHjD5kguK4UnD7Zgin/4DbTBh1N1xk1dNWT1+e7OwmbA3dg7ILUMyn6Lv4xsEYgfjEgDV1SUhnAUET5uBi0vEjJdUxYW+7wvzuy/LDe4bqmJCehXCTO6l7MRmbtcx+iiG5Zo8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=L8c3DlKH; 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="L8c3DlKH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 16B34C2BCB8; Sat, 9 May 2026 03:22:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778296952; bh=JFEbBbQppXOY0TFs2/qsQyNSm+VEc8Wki5HFbwZxZZI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L8c3DlKHWpFiTgWHLMj6y5QBXPNBQppR5/ZY0Lbf/JTr0ELubmZgtauOi5SNzckMP EKyjDGus47T8c/bhQzmCoZFo54pnc/a2AVpDkR+UjgE2n1+wgPjO5gzbdFTHcyDtJG MMQJKHIlEVsxf5dI1hiTjorrKXKbGvkPSQw2Phw1dJiNuVcZx7TNka/U4lMecHx0ji 15z0VsLZcv0mqD7HiMcCpIzhANwwBsIe650q48QqQZrBxJBd7+0rEl4Nt+91dr6SwI gN0WnE9ZPAmwZ220i/cA+hI3uhcfVEiqpRv00+jRnPxHaOvg0YshS8ZNzh8B3KsJRj 5pY/IKU5lPhKQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Junrui Luo , Yuhao Jiang , Gao Xiang , Sasha Levin Subject: [PATCH 6.18.y 2/2] erofs: fix unsigned underflow in z_erofs_lz4_handle_overlap() Date: Fri, 8 May 2026 23:22:29 -0400 Message-ID: <20260509032229.3064816-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260509032229.3064816-1-sashal@kernel.org> References: <2026050413-commute-discourse-5f47@gregkh> <20260509032229.3064816-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- fs/erofs/decompressor.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c index 2f4cef67cf640..e4e59a4e0d90d 100644 --- a/fs/erofs/decompressor.c +++ b/fs/erofs/decompressor.c @@ -142,6 +142,7 @@ 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] != -- 2.53.0