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cifs: Do not leak EDEADLK to dgetents64 for STATUS_USER_SESSION_DELETED

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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>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Ronnie Sahlberg 2021-08-25 21:16:56 +10:00 committed by Steve French
parent 332c404a55
commit 3998f0b8bc
1 changed files with 22 additions and 1 deletions
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23
fs/cifs/readdir.c
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@ -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 @@ error_exit:
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)
{