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From: Ronnie Sahlberg <lsahlber@redhat.com>
To: linux-cifs <linux-cifs@vger.kernel.org>
Cc: Steve French <smfrench@gmail.com>
Subject: [PATCH] cifs: Do not leak EDEADLK to dgetents64 for STATUS_USER_SESSION_DELETED
Date: Wed, 25 Aug 2021 17:30:43 +1000	[thread overview]
Message-ID: <20210825073043.1630555-2-lsahlber@redhat.com> (raw)
In-Reply-To: <20210825073043.1630555-1-lsahlber@redhat.com>

RHBZ: 1994393

If we hit a STATUS_USER_SESSION_DELETED for the Create part in the
Create/QueryDirectory compound that starts a directory scan
we will leak EDEADLK back to userspace and surprise glibc and the application.

Pick this up cifs_readdir() and retry a small number of tries before we
return an error to userspace.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
---
 fs/cifs/readdir.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index bfee176b901d..56e5d456366d 100644
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -930,6 +930,7 @@ int cifs_readdir(struct file *file, struct dir_context *ctx)
 	unsigned int max_len;
 	const char *full_path;
 	void *page = alloc_dentry_path();
+	int retry_count = 0;
 
 	xid = get_xid();
 
@@ -944,8 +945,15 @@ int cifs_readdir(struct file *file, struct dir_context *ctx)
 	 * '..'. Otherwise we won't be able to notify VFS in case of failure.
 	 */
 	if (file->private_data == NULL) {
+		again:
 		rc = initiate_cifs_search(xid, file, full_path);
-		cifs_dbg(FYI, "initiate cifs search rc %d\n", rc);
+		if (rc == -EDEADLK && retry_count++ < 5) {
+			/*
+			 * We don't have enough credits to start reading the
+			 * directory so just try again.
+			 */
+			goto again;
+		}
 		if (rc)
 			goto rddir2_exit;
 	}
-- 
2.30.2


  reply	other threads:[~2021-08-25  7:31 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-25  7:30 [PATCH 0/1] cifs: do not leak EDEADLK to dgetents64 Ronnie Sahlberg
2021-08-25  7:30 ` Ronnie Sahlberg [this message]
2021-08-25 11:16 [PATCH 0/1] don't leak EDEADLK to userspace Ronnie Sahlberg
2021-08-25 11:16 ` [PATCH] cifs: Do not leak EDEADLK to dgetents64 for STATUS_USER_SESSION_DELETED Ronnie Sahlberg
2021-08-25 21:09   ` Steve French
2021-08-26 17:15     ` Shyam Prasad N
2021-08-26 18:07       ` ronnie sahlberg

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