lightly updated to add short sleep before retry
On Wed, Aug 25, 2021 at 6:17 AM Ronnie Sahlberg <lsahlber@xxxxxxxxxx> wrote:
>
> 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@xxxxxxxxxxxxxxx
> Reported-by: Xiaoli Feng <xifeng@xxxxxxxxxx>
> Signed-off-by: Ronnie Sahlberg <lsahlber@xxxxxxxxxx>
> ---
> 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
>
--
Thanks,
Steve
From 57cea50fa5a30068752a8155e1c7230c8c585493 Mon Sep 17 00:00:00 2001
From: Ronnie Sahlberg <lsahlber@xxxxxxxxxx>
Date: Wed, 25 Aug 2021 21:16:56 +1000
Subject: [PATCH] cifs: Do not leak EDEADLK to dgetents64 for
STATUS_USER_SESSION_DELETED
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@xxxxxxxxxxxxxxx
Reported-by: Xiaoli Feng <xifeng@xxxxxxxxxx>
Signed-off-by: Ronnie Sahlberg <lsahlber@xxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
---
fs/cifs/readdir.c | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)
diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index bfee176b901d..54d77c99e21c 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 +451,27 @@ 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);
+ /*
+ * If we don't have enough credits to start reading the
+ * directory just try again after short wait.
+ */
+ if (rc != -EDEADLK)
+ break;
+
+ usleep_range(512, 2048);
+ } while (retry_count++ < 5);
+
+ return rc;
+}
+
/* return length of unicode string in bytes */
static int cifs_unicode_bytelen(const char *str)
{
--
2.30.2
