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 EB79F2E2F0E; Mon, 4 May 2026 14:05:36 +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=1777903537; cv=none; b=mrtdhWHKvALHSkxr3/xvEx5ZxHbg0/0tmXANaRZqxoRZcn+3bOZsIbltMpG9CIScIGhBlQ03I3iybonC/1p4e8UFr/L4Rox6HIbnnY4LkhIj4mz/1soJ2+r6oK8zntp8u/VqLrgVp2CTFjLTswYH2CTA4wniX3LBD3HlZQjZm8s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777903537; c=relaxed/simple; bh=bWDFVvKZlkb0VqHYI3d3+Yb/iW0fbZJ4xqLEDfYtjpM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=o/gfmyiXeGeV1SBG5FXZa/mvX624ILzgCqiFDBXe5o1kRV4GtLwBklUHms+i8mrwoioVxR7y08R0yr1jvE0QgKgj9P4iXYpTm3kjG/gYmTlRJ90pN3dgSgpMKIX+jqmMVGDpwwRoTQVFuo+YlF3PJkjkP5TT8PPFN5XTSRZkzSs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=bkYcid8J; 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="bkYcid8J" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 81071C2BCF4; Mon, 4 May 2026 14:05:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1777903536; bh=bWDFVvKZlkb0VqHYI3d3+Yb/iW0fbZJ4xqLEDfYtjpM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bkYcid8JbwHYQ8Hf1F4oOVgviENmC3druQWj8EwUceXvZ9xEiAF9QsM4E75p3aboX 9f4w907pAw1iT5nXRwUqtYZi4regfTSvlIuUHcR+WufhDvo/bX+6QKFNh+0Cd7vMLf F47FBaaT2bbprMl50LVJDdCww6gTW3qIjw8Ucc/o= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yuhao Jiang , Junrui Luo , Gao Xiang Subject: [PATCH 7.0 271/307] erofs: fix unsigned underflow in z_erofs_lz4_handle_overlap() Date: Mon, 4 May 2026 15:52:36 +0200 Message-ID: <20260504135153.003977544@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260504135142.814938198@linuxfoundation.org> References: <20260504135142.814938198@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 7.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Junrui Luo commit 21e161de2dc660b1bb70ef5b156ab8e6e1cca3ab upstream. 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: Greg Kroah-Hartman --- fs/erofs/decompressor.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/erofs/decompressor.c +++ b/fs/erofs/decompressor.c @@ -145,6 +145,7 @@ 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] !=