From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-100.freemail.mail.aliyun.com (out30-100.freemail.mail.aliyun.com [115.124.30.100]) (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 038681BD9C9; Thu, 16 Apr 2026 06:03:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.100 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776319397; cv=none; b=rJLSNEF/8p9VfhyvlMOHtgqmXG84lJ8AbIQAsqEWU5PSnxdeLANKuXZR0ZTU95/1zaOZB90HSAEsCt6g5xvnYf06/0RLzb6sd/bEaFAuEePbZdgOGg+dc5LfFU5CesMdIQL9AvERtvp8nsmEOQpgyJ67OErPSpwMGMOg91/AQQQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776319397; c=relaxed/simple; bh=jzW/IRXsD0pARdFJ7w3GkHpIKhal7AiE+1QIw2RRcTE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Y+PDHiRCgvNCBy/Q5hv4PoRs1VwmEZY6RUZgDJFjAPuFmXO0Mpq5TRRABAjEm/hOlFpOGSA4vCUwO8Haj6i7cc7ofFVcpjVkgtKrz1H4FWDyMs9SmywdKlVPlOQkZdVScXDKlhTfW+Dsgv77lmzImw/Ek8fyF8ZrOvv1rUOeABE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=E8xBb1Nt; arc=none smtp.client-ip=115.124.30.100 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="E8xBb1Nt" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1776319390; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=ZomflwDXNwqG6gSK6tClB89Uhm5LpUQnhTnVd8IiJTo=; b=E8xBb1NttxcwuBBLXU510O/o0tnoS64v1WLaneTJE3cXe1jrCVB3+CXk9UxWDbIAhAgz012yVY2Ky/xGUcRXH/zAmdti0cjhR805NwjZ5NAP8PcrYZJwrzNymYnhtb1XoWxKSTylDsdFwMQJbI3JxnwdJpiL4EQCNR0YfnqRWzI= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R931e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037009110;MF=hsiangkao@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0X17IOFV_1776319385; Received: from x31i01179.sqa.na131.tbsite.net(mailfrom:hsiangkao@linux.alibaba.com fp:SMTPD_---0X17IOFV_1776319385 cluster:ay36) by smtp.aliyun-inc.com; Thu, 16 Apr 2026 14:03:10 +0800 From: Gao Xiang To: linux-erofs@lists.ozlabs.org Cc: LKML , Gao Xiang , Yuhao Jiang , Junrui Luo , stable@vger.kernel.org Subject: [PATCH] erofs: fix the out-of-bounds nameoff handling for trailing dirents Date: Thu, 16 Apr 2026 14:03:05 +0800 Message-ID: <20260416060305.3129334-1-hsiangkao@linux.alibaba.com> X-Mailer: git-send-email 2.43.5 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Currently we already have boundary-checks for nameoffs, but the trailing dirents are special since the namelens are calculated with strnlen() with unchecked nameoffs. If a crafted EROFS has a trailing dirent with nameoff >= maxsize, maxsize - nameoff can underflow, causing strnlen() to read past the directory block. Fixes: 3aa8ec716e52 ("staging: erofs: add directory operations") Fixes: 33bac912840f ("staging: erofs: keep corrupted fs from crashing kernel in erofs_readdir()") Reported-by: Yuhao Jiang Reported-by: Junrui Luo Closes: https://lore.kernel.org/r/A0FD7E0F-7558-49B0-8BC8-EB1ECDB2479A@outlook.com Cc: stable@vger.kernel.org Signed-off-by: Gao Xiang --- fs/erofs/dir.c | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-) diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c index e5132575b9d3..ecfac9b49322 100644 --- a/fs/erofs/dir.c +++ b/fs/erofs/dir.c @@ -19,20 +19,18 @@ static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx, const char *de_name = (char *)dentry_blk + nameoff; unsigned int de_namelen; - /* the last dirent in the block? */ - if (de + 1 >= end) - de_namelen = strnlen(de_name, maxsize - nameoff); - else + /* non-trailing dirent in the directory block? */ + if (de + 1 < end) de_namelen = le16_to_cpu(de[1].nameoff) - nameoff; + else if (maxsize <= nameoff) + goto err_bogus; + else + de_namelen = strnlen(de_name, maxsize - nameoff); - /* a corrupted entry is found */ - if (nameoff + de_namelen > maxsize || - de_namelen > EROFS_NAME_LEN) { - erofs_err(dir->i_sb, "bogus dirent @ nid %llu", - EROFS_I(dir)->nid); - DBG_BUGON(1); - return -EFSCORRUPTED; - } + /* a corrupted entry is found (including negative namelen) */ + if (!clamp_t(unsigned int, de_namelen, 1, EROFS_NAME_LEN) || + nameoff + de_namelen > maxsize) + goto err_bogus; if (!dir_emit(ctx, de_name, de_namelen, erofs_nid_to_ino64(EROFS_SB(dir->i_sb), @@ -42,6 +40,10 @@ static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx, ctx->pos += sizeof(struct erofs_dirent); } return 0; +err_bogus: + erofs_err(dir->i_sb, "bogus dirent @ nid %llu", EROFS_I(dir)->nid); + DBG_BUGON(1); + return -EFSCORRUPTED; } static int erofs_readdir(struct file *f, struct dir_context *ctx) -- 2.43.5