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From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Steve French <stfrench@microsoft.com>,
	Ronnie Sahlberg <lsahlber@redhat.com>
Cc: linux-cifs@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: build_path_from_dentry_optional_prefix() may schedule from invalid context
Date: Thu, 29 Aug 2019 14:02:37 +0900	[thread overview]
Message-ID: <20190829050237.GA5161@jagdpanzerIV> (raw)

Hello,

Looking at commit "cifs: create a helper to find a writeable handle
by path name":

->open_file_lock scope is atomic context, while build_path_from_dentry()
can schedule - kmalloc(GFP_KERNEL)

       spin_lock(&tcon->open_file_lock);
       list_for_each(tmp, &tcon->openFileList) {
               cfile = list_entry(tmp, struct cifsFileInfo,
                            tlist);
               full_path = build_path_from_dentry(cfile->dentry);
               if (full_path == NULL) {
                       spin_unlock(&tcon->open_file_lock);
                       return -ENOMEM;
               }
               if (strcmp(full_path, name)) {
                       kfree(full_path);
                       continue;
               }
               kfree(full_path);

               cinode = CIFS_I(d_inode(cfile->dentry));
               spin_unlock(&tcon->open_file_lock);
               return cifs_get_writable_file(cinode, 0, ret_file);
       }

       spin_unlock(&tcon->open_file_lock);

Additionally, kfree() can (and should) be done outside of
->open_file_lock scope.

	-ss

             reply	other threads:[~2019-08-29  5:02 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-29  5:02 Sergey Senozhatsky [this message]
2019-09-20  0:11 ` build_path_from_dentry_optional_prefix() may schedule from invalid context Pavel Shilovsky
2019-09-21 22:38   ` Al Viro
2019-09-30 17:32     ` Pavel Shilovsky
2019-12-09  0:34       ` Al Viro
2019-12-10 19:14         ` Pavel Shilovsky

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