From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f199.google.com (mail-oi1-f199.google.com [209.85.167.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5671F442B30 for ; Fri, 24 Jul 2026 23:42:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784936523; cv=none; b=nvKAxfNtYxuVEzpu4AuElwdSU8MBVnDi3IUUPIgfFr4X+F75b+j21mRDn7OZoNS/vrCSU887Pw/EwsqtqvYqYfCWOd0JDZDONAdY0GW10xysZonPu4B2eDQGjAr09P/fqlNxKwsYp5Yxe5UqQl7ik8Ln9Mp6dCh6BNJT30jPvSY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784936523; c=relaxed/simple; bh=fBgETPo3+oeW6Skb+MF8HxPCy5aQQWvv5xC+dPRvgzE=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; b=gHHG7l7a0WdfJgQHGvDK+YZbC7A9OaTyr3ibBRFRMKirDPI3QY5ne0fLoWiID43uqnDL5jB2cshGCwaG7RU11A+N3zkExh0RGin9J9bPi28egwT0577TbUxnNj22bzeShpI2YwgF8N1A39VXRMss7VlSSf3uTPYq2HlyPcAdUyc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.167.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oi1-f199.google.com with SMTP id 5614622812f47-4909b046dabso1357608b6e.0 for ; Fri, 24 Jul 2026 16:41:59 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1784936518; x=1785541318; h=content-type:to:from:subject:message-id:in-reply-to:date :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to:content-type; bh=18fVvI8ycx3GGUE85WgK9s7F04gVp8kjofKoVTZQuvc=; b=c8/1Ca6GcZeEa21wfbGd/wwA+o5Hd7heYMLgGNrZElE614nIYYld1VabIopfPCkjAi gaEq7gh5loJo6BuspMRne4wVZT3qFH+HOOyyGOBS5XqSJwl9lNU5Ojbi0P+YAM0siM0C yGQ8JRE5xa47qooEymBcpdkYw9eZN7xUaxfTUaCxw3kkMt42tm85PbLBAiEQkkg7RlfZ F+OrO1QUam2cMzNmCsMJWfdPk80huBkvjDbTelFgiSb7/BxasgGt9TA3c0IyxKR23kAT zt0eyYt5tgtbX6ZJkkkphVEwAdwuWELZuU/fCZE1pvxKuvoW/5ZqL7GFFuHIHV+cZk16 SaEQ== X-Gm-Message-State: AOJu0Yw8RQ+gX3r190sa51VvXEMMARulWj4d8K8OHSnhlw9Jc0v5YUDk 6F9pz1ueBIPakJ1YLLPKcRYYz5ugkK4LH31MkcTB01WUUESaQYqD+C9RavM4N/3wMvkrS2muECz BX/DaTdelnOQdmRJApmPZi/Tj+y2f5xxJuahsg3xCb0Sh8ByECbpFkh8M/y0= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:23ca:b0:495:f74a:b572 with SMTP id 5614622812f47-4ab69f31afdmr719748b6e.5.1784936518186; Fri, 24 Jul 2026 16:41:58 -0700 (PDT) Date: Fri, 24 Jul 2026 16:41:58 -0700 In-Reply-To: <6a62f788.dde6c935.cf6c8.000e.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a63f846.70955b6c.323240.000c.GAE@google.com> Subject: Forwarded: [PATCH] 9p: add printk diagnostics to identify -ENOENT source in v9fs_fid_lookup From: syzbot To: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com. *** Subject: [PATCH] 9p: add printk diagnostics to identify -ENOENT source in v9fs_fid_lookup Author: kartikey406@gmail.com #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master Add printk(KERN_WARNING) at the three points in v9fs_fid_lookup_with_uid() where a racing unlink/rename can cause a symlink fid walk to fail, to determine which one produces the -ENOENT seen in the "WARNING in v9fs_init_request (2)" reproducer. Diagnostic only, not a functional fix. Reported-by: syzbot+344c09c64fcd8d3d2782@syzkaller.appspotmail.com Signed-off-by: Deepanshu Kartikey --- fs/9p/fid.c | 10 ++++++++++ fs/9p/vfs_addr.c | 37 ++++++++++++++++++++++++------------- 2 files changed, 34 insertions(+), 13 deletions(-) diff --git a/fs/9p/fid.c b/fs/9p/fid.c index 76242d450aa7..d8d79a4c88ef 100644 --- a/fs/9p/fid.c +++ b/fs/9p/fid.c @@ -194,6 +194,10 @@ static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry, old_fid = fid; fid = p9_client_walk(old_fid, 1, &dentry->d_name.name, 1); + if (IS_ERR(fid)) { + printk(KERN_WARNING "DIAG: single-component p9_client_walk " + "failed, name=%pd err=%ld\n", dentry, PTR_ERR(fid)); + } p9_fid_put(old_fid); goto fid_out; } @@ -251,6 +255,9 @@ static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry, old_fid = fid; } if (IS_ERR(fid)) { + printk(KERN_WARNING "DIAG: multipath p9_client_walk failed, " + "name=%pd component_index=%d err=%ld\n", + dentry, i, PTR_ERR(fid)); kfree(wnames); goto err_out; } @@ -262,6 +269,9 @@ static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry, spin_lock(&dentry->d_lock); if (d_unhashed(dentry)) { spin_unlock(&dentry->d_lock); + printk(KERN_WARNING "DIAG: walk succeeded but dentry " + "unhashed, manufacturing -ENOENT, name=%pd\n", + dentry); p9_fid_put(fid); fid = ERR_PTR(-ENOENT); } else { diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c index 1ac0b3dcc077..fc05bd963506 100644 --- a/fs/9p/vfs_addr.c +++ b/fs/9p/vfs_addr.c @@ -136,21 +136,37 @@ static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file) if (file) { fid = file->private_data; - if (!fid) - goto no_fid; + if (!fid) { + WARN_ONCE(1, "DIAG: v9fs_init_request: file has no fid, " + "inode->i_ino=%llx\n", rreq->inode->i_ino); + return -EINVAL; + } p9_fid_get(fid); } else if (S_ISLNK(rreq->inode->i_mode)) { dentry = d_find_any_alias(rreq->inode); - if (!dentry) - goto no_fid; + if (!dentry) { + WARN_ONCE(1, "DIAG: v9fs_init_request: symlink inode has no " + "dentry alias, inode->i_ino=%llx\n", + rreq->inode->i_ino); + return -EINVAL; + } fid = v9fs_fid_lookup(dentry); + if (IS_ERR(fid)) { + WARN_ONCE(1, "DIAG: v9fs_init_request: v9fs_fid_lookup failed " + "for symlink, err=%ld dentry=%pd4 inode->i_ino=%llx\n", + PTR_ERR(fid), dentry, rreq->inode->i_ino); + dput(dentry); + return PTR_ERR(fid); + } dput(dentry); - if (IS_ERR(fid)) - goto no_fid; } else { fid = v9fs_fid_find_inode(rreq->inode, writing, INVALID_UID, true); - if (!fid) - goto no_fid; + if (!fid) { + WARN_ONCE(1, "DIAG: v9fs_init_request: non-symlink inode has " + "no open/writeback fid, inode->i_ino=%llx\n", + rreq->inode->i_ino); + return -EINVAL; + } } rreq->wsize = fid->clnt->msize - P9_IOHDRSZ; @@ -163,11 +179,6 @@ static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file) WARN_ON(rreq->origin == NETFS_READ_FOR_WRITE && !(fid->mode & P9_ORDWR)); rreq->netfs_priv = fid; return 0; - -no_fid: - WARN_ONCE(1, "folio expected an open fid inode->i_ino=%llx\n", - rreq->inode->i_ino); - return -EINVAL; } /** -- 2.43.0