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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 21:16:56 +1000	[thread overview]
Message-ID: <20210825111656.1635954-2-lsahlber@redhat.com> (raw)
In-Reply-To: <20210825111656.1635954-1-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 initiate_cifs_search() and retry a small number of tries before we
return an error to userspace.

Cc: stable@vger.kernel.org
Reported-by: Xiaoli Feng <xifeng@redhat.com>
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
---
 fs/cifs/readdir.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index bfee176b901d..4518e3ca64df 100644
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -369,7 +369,7 @@ int get_symlink_reparse_path(char *full_path, struct cifs_sb_info *cifs_sb,
  */
 
 static int
-initiate_cifs_search(const unsigned int xid, struct file *file,
+_initiate_cifs_search(const unsigned int xid, struct file *file,
 		     const char *full_path)
 {
 	__u16 search_flags;
@@ -451,6 +451,23 @@ initiate_cifs_search(const unsigned int xid, struct file *file,
 	return rc;
 }
 
+static int
+initiate_cifs_search(const unsigned int xid, struct file *file,
+		     const char *full_path)
+{
+	int rc, retry_count = 0;
+
+	do {
+		rc = _initiate_cifs_search(xid, file, full_path);
+		/*
+		 * We don't have enough credits to start reading the
+		 * directory so just try again.
+		 */
+	} while (rc == -EDEADLK && retry_count++ < 5);
+
+	return rc;
+}
+
 /* return length of unicode string in bytes */
 static int cifs_unicode_bytelen(const char *str)
 {
-- 
2.30.2


  reply	other threads:[~2021-08-25 11:17 UTC|newest]

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

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