From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794049398; b=VpEe2u+QliC3mtuFs5dic0NOGVrP8tG/B/imvdAzZdMp5i0aSp41hlMvibfukH1SyVJG sjVj0daUnPzqz8135P+cX6ytcZiYDc3liMM8CHgrN77Xisf3Kk2eZ0Vty9W0SLmyPcrDd mFnXyXqqevcstbl9b53UwrpQcS9NEcdCA2fR0HPmnyVSR82c8vKUrBzWjqzBbL6vbAAwR sBt1Be2a4CeHkvtixMHPp10uYuWF8rIntrSQgf73Ln6+fXGZV4ZR+2r/2rYGsSyb28zd8 Tjr7C2oTygIHdk85zC2cF0Fa9c6u2L37/vv6RB4XrsqjY9kJTM9Ic7RLy0RHg3ZzFaw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794049398; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=lLNxY2FvuUbZbYXwOR8D/52SNJvQV57H4oWjxlW5e14=; b=5fccAyosOpYjFM/Y6mqGgd9MXQCs3HiK76ltYXv4vb8v2yrBCxa9+PFnod7WHrSMxI2U 4iKKTXYUPolTClwcevjKkoBiiUHLB8+OFwu4SEXCMbTLgK6lyH3EoEIsUIzXgCELZyWBj BVFy5QwliYOLA0aJoWrJK8tpXPXtQWcLD+b8e7Mgio34xoRSjn/WiD7EL+7aMKs3eQH6t /XTJmyRyC6bZzAYPt6M/M1ASzSMqgUKUIm5hWwNHramvQ+yCQ+UPNWsXL8Bs6ns29qJHc POCyXaNmN0luawoQMOSGrPsGds4Su+0HUy+s/FMml5o7KGnajoJz4jG+lEwKxNQUHpg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=V44HXckX; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7F601606A326 for ; Sat, 7 Nov 2026 11:03:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=V44HXckX Received: by smtp.kernel.org (Postfix) with ESMTPSA id DB9621F0089F; Sat, 7 Nov 2026 11:03:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794049398; bh=lLNxY2FvuUbZbYXwOR8D/52SNJvQV57H4oWjxlW5e14=; h=From:To:Cc:Subject:Date; b=V44HXckXxxh6doTteNknEOnin0IQpM7MF5o5OX9nK0IpSv4VVbwtK27aeC7Lh0KCv 3k+2X95YjJK0mEnuBNt25NDQOG9/PwNaku6o86WKIV4U5gRfIrnZ/n8DJP2kBhfqgz uwCw5gHaCPri2ad54xrQp9FsIthE5LxfXn5PArIus9cHChycU2x68eFpBzKt4s6kN6 7acACPY4BnZaLh3YZpsAp8Rp+LwDVF70YLFbCxaiRZhvHfTevTxIGjc9FKhHSE84uw 6jKn9Zdr9FJR0YeSdy4nmywmcNE3O/JeyemjMg1UTyDUkqgEBMdVHGEsxEwMfKmK3m EfelpOeMyJH8g== From: Sasha Levin To: southampton.jake.labelle@gmail.com, konishi.ryusuke@gmail.com, slava@dubeyko.com Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] nilfs2: validate directory position after llseek in readdir" failed to apply to 5.15-stable tree Date: Sat, 7 Nov 2026 06:03:16 -0500 Message-ID: <20261107060316-failed-5.15-de7f49c12566@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x de7f49c12566cc5c7437a2f26c6c754b9d4d5648 # git commit -s git send-email --to '' --in-reply-to '20261107060316-failed-5.15-de7f49c12566@kernel.org' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From de7f49c12566cc5c7437a2f26c6c754b9d4d5648 Mon Sep 17 00:00:00 2001 From: Jake Labelle Date: Thu, 8 Oct 2026 20:52:48 +0900 Subject: [PATCH] nilfs2: validate directory position after llseek in readdir nilfs_readdir() uses ctx->pos, which userspace can set to an arbitrary value via llseek, as an offset into the directory folio and parses whatever bytes sit there as a directory entry. A position pointing into the middle of an entry -- or at unused bytes of a corrupted image that the page validator never inspected -- makes dir_emit() copy up to 255 (name_len) bytes from a bogus entry, possibly reading past the end of the folio and returning unrelated memory contents to userspace. Snap unaligned positions onto a valid entry boundary by walking the rec_len chain from the chunk start before parsing, as ext2 does in ext2_validate_entry(). [ryusuke: fixed offset wrap-around in nilfs_validate_entry() and conformed AI tag to guidelines] Fixes: 2ba466d74ed7 ("nilfs2: directory entry operations") Assisted-by: Claude:claude-mythos-5 Signed-off-by: Jake Labelle Cc: stable@vger.kernel.org Signed-off-by: Ryusuke Konishi Signed-off-by: Viacheslav Dubeyko --- fs/nilfs2/dir.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/fs/nilfs2/dir.c b/fs/nilfs2/dir.c index 8b53802b6ebd7..7686ca9228fc8 100644 --- a/fs/nilfs2/dir.c +++ b/fs/nilfs2/dir.c @@ -231,11 +231,27 @@ static struct nilfs_dir_entry *nilfs_next_entry(struct nilfs_dir_entry *p) nilfs_rec_len_from_disk(p->rec_len)); } +static inline unsigned int +nilfs_validate_entry(char *base, unsigned int offset, unsigned int mask) +{ + struct nilfs_dir_entry *de = (struct nilfs_dir_entry *)(base + offset); + struct nilfs_dir_entry *p = + (struct nilfs_dir_entry *)(base + (offset & mask)); + + while ((char *)p < (char *)de) { + if (p->rec_len == 0) + break; + p = nilfs_next_entry(p); + } + return (char *)p - base; +} + static int nilfs_readdir(struct file *file, struct dir_context *ctx) { loff_t pos = ctx->pos; struct inode *inode = file_inode(file); struct super_block *sb = inode->i_sb; + unsigned int chunk_size = nilfs_chunk_size(inode); unsigned int offset = pos & ~PAGE_MASK; unsigned long n = pos >> PAGE_SHIFT; unsigned long npages = dir_pages(inode); @@ -254,6 +270,24 @@ static int nilfs_readdir(struct file *file, struct dir_context *ctx) ctx->pos += PAGE_SIZE - offset; return -EIO; } + /* + * ctx->pos comes from userspace via llseek and may point + * into the middle of an entry -- or at unvalidated bytes + * of a crafted image. offset is only nonzero here on the + * very first iteration (subsequent pages always start at + * offset 0, which -- like any chunk boundary -- is always + * a legitimate entry start, since no rec_len chain crosses + * a chunk boundary). Snap a non-chunk-aligned offset onto + * a real entry boundary by walking the chain from the + * enclosing chunk's start, as ext2 does; otherwise + * dir_emit() copies name_len bytes from a fake entry, + * reading past the end of the folio. + */ + if (offset & (chunk_size - 1)) { + offset = nilfs_validate_entry(kaddr, offset, + ~(chunk_size - 1)); + ctx->pos = ((loff_t)n << PAGE_SHIFT) + offset; + } de = (struct nilfs_dir_entry *)(kaddr + offset); limit = kaddr + nilfs_last_byte(inode, n) - NILFS_DIR_REC_LEN(1); -- 2.53.0