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 24CE92F617C; Sat, 12 Sep 2026 18:44:54 +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=1789238695; cv=none; b=OXxidl8DhHTt1FIsj6rA4XR7iX8OIFpJNbTrU3sUEtvjwUIi9FQdQXH900FYehP3o0Zzmi3iucRpzhplPJIkDJALfw+0Ib1DtFI6l1KsoUvemlm8+uPKM8F9MGFoYP7C+uZibO+RlyJnUdzYDDXoJYxY8ZogYB+9GPTrgfokGjw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789238695; c=relaxed/simple; bh=fu5H6qLRq0K8edLeeIGd3PYBSFCnzNxc85CRYft5mpo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=THLB+DsjWwrBAJT3WMF/nmzoC3eFfi5qkrw7Ph9l+9PY56uqjKKoHWQ9Hzz2vXWJDT/FTwGEnqi+AoQYgknKgsZ1LhMcX/Nw0fM7OoFq7rbyqX/mIpnVQSm78TIuS4+GWhcOgsbuM7eaprKZ/eFXT1Bm51WUmcQIowvyXvdTG2c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=hotDng4m; 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="hotDng4m" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D69851F000FF; Sat, 12 Sep 2026 18:44:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789238694; bh=+O2In1mIO0FOPsTxbs40VjUFoqQB7/y9Y2f9D3738P0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=hotDng4muBM+AeKQfRoQljzrvV2oAeTK3d9uMQJsn38mOCRlz5oxEV63jDIwbxnHi 1U5p85F6m+XtAMFG0n3FyEeZWnTJn415sJ2sS+bvnV3yGQy6VZOiniPr3381mclXtw gFcr0rsuxL1A2BbREsfLiSAWVZ7KECTmT2t+jUpM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Weiming Shi , Xiang Mei , Jan Kara , Sasha Levin Subject: [PATCH 5.15 514/935] isofs: fix out-of-bounds page array access on empty zisofs block Date: Sat, 12 Sep 2026 08:59:04 +0200 Message-ID: <20260912065538.611272350@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065526.833703348@linuxfoundation.org> References: <20260912065526.833703348@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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xiang Mei [ Upstream commit 68d4d3e78150c7ed7d1195af63ad1e6ace30c661 ] zisofs_uncompress_block()'s empty-block fast path returns pcount << PAGE_SHIFT, ignoring the incoming poffset, unlike the decompression path which returns bytes produced relative to poffset. zisofs_fill_pages() uses that return to advance its page cursor, so when the zisofs block size is below PAGE_SIZE and a sub-page block leaves poffset partway into a page, a following empty block over-counts and advances pages[] one element past its end, after which "if (poffset && *pages)" reads pages[1] out of bounds. rock.c only rejects a block-size shift > 17, so a crafted "ZF" Rock Ridge record can set it below PAGE_SHIFT; the bug is reached by an ordinary read() of a compressed file on such a mounted ISO9660 image. Return the byte count relative to poffset and zero only [poffset, PAGE_SIZE) of the first page, matching the decompression path. The page-aligned case (poffset == 0) is unaffected. BUG: KASAN: slab-out-of-bounds in zisofs_read_folio (fs/isofs/compress.c:290) Read of size 8 at addr ffff88800f5eac48 by task exploit/142 zisofs_read_folio (fs/isofs/compress.c:290) read_pages (mm/readahead.c:184) ... filemap_read (mm/filemap.c:2814) vfs_read (fs/read_write.c:574) __x64_sys_pread64 (fs/read_write.c:769) do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) The buggy address is located 0 bytes to the right of the allocated 8-byte region in the kmalloc-8 cache Fixes: 59bc055211b8 ("zisofs: Implement reading of compressed files when PAGE_CACHE_SIZE > compress block size") Reported-by: Weiming Shi Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Xiang Mei Link: https://patch.msgid.link/20260712234150.3213467-1-xmei5@asu.edu Signed-off-by: Jan Kara Signed-off-by: Sasha Levin --- fs/isofs/compress.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/isofs/compress.c b/fs/isofs/compress.c index f2deec0df49c5..b81415e73aaf4 100644 --- a/fs/isofs/compress.c +++ b/fs/isofs/compress.c @@ -65,12 +65,14 @@ static loff_t zisofs_uncompress_block(struct inode *inode, loff_t block_start, /* Empty block? */ if (block_size == 0) { for ( i = 0 ; i < pcount ; i++ ) { + unsigned int off = i ? 0 : poffset; + if (!pages[i]) continue; - memzero_page(pages[i], 0, PAGE_SIZE); + memzero_page(pages[i], off, PAGE_SIZE - off); SetPageUptodate(pages[i]); } - return ((loff_t)pcount) << PAGE_SHIFT; + return (((loff_t)pcount) << PAGE_SHIFT) - poffset; } /* Because zlib is not thread-safe, do all the I/O at the top. */ -- 2.53.0