--- /dev/null
+From 28eb24ff75c5ac130eb326b3b4d0dcecfc0f427d Mon Sep 17 00:00:00 2001
+From: Paulo Alcantara <paulo@paulo.ac>
+Date: Tue, 20 Nov 2018 15:16:36 -0200
+Subject: cifs: Always resolve hostname before reconnecting
+
+From: Paulo Alcantara <paulo@paulo.ac>
+
+commit 28eb24ff75c5ac130eb326b3b4d0dcecfc0f427d upstream.
+
+In case a hostname resolves to a different IP address (e.g. long
+running mounts), make sure to resolve it every time prior to calling
+generic_ip_connect() in reconnect.
+
+Suggested-by: Steve French <stfrench@microsoft.com>
+Signed-off-by: Paulo Alcantara <palcantara@suse.de>
+Signed-off-by: Steve French <stfrench@microsoft.com>
+Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ fs/cifs/connect.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
+ 1 file changed, 53 insertions(+)
+
+--- a/fs/cifs/connect.c
++++ b/fs/cifs/connect.c
+@@ -48,6 +48,7 @@
+ #include "cifs_unicode.h"
+ #include "cifs_debug.h"
+ #include "cifs_fs_sb.h"
++#include "dns_resolve.h"
+ #include "ntlmssp.h"
+ #include "nterr.h"
+ #include "rfc1002pdu.h"
+@@ -307,6 +308,53 @@ static int cifs_setup_volume_info(struct
+ const char *devname);
+
+ /*
++ * Resolve hostname and set ip addr in tcp ses. Useful for hostnames that may
++ * get their ip addresses changed at some point.
++ *
++ * This should be called with server->srv_mutex held.
++ */
++#ifdef CONFIG_CIFS_DFS_UPCALL
++static int reconn_set_ipaddr(struct TCP_Server_Info *server)
++{
++ int rc;
++ int len;
++ char *unc, *ipaddr = NULL;
++
++ if (!server->hostname)
++ return -EINVAL;
++
++ len = strlen(server->hostname) + 3;
++
++ unc = kmalloc(len, GFP_KERNEL);
++ if (!unc) {
++ cifs_dbg(FYI, "%s: failed to create UNC path\n", __func__);
++ return -ENOMEM;
++ }
++ snprintf(unc, len, "\\\\%s", server->hostname);
++
++ rc = dns_resolve_server_name_to_ip(unc, &ipaddr);
++ kfree(unc);
++
++ if (rc < 0) {
++ cifs_dbg(FYI, "%s: failed to resolve server part of %s to IP: %d\n",
++ __func__, server->hostname, rc);
++ return rc;
++ }
++
++ rc = cifs_convert_address((struct sockaddr *)&server->dstaddr, ipaddr,
++ strlen(ipaddr));
++ kfree(ipaddr);
++
++ return !rc ? -1 : 0;
++}
++#else
++static inline int reconn_set_ipaddr(struct TCP_Server_Info *server)
++{
++ return 0;
++}
++#endif
++
++/*
+ * cifs tcp session reconnection
+ *
+ * mark tcp session as reconnecting so temporarily locked
+@@ -403,6 +451,11 @@ cifs_reconnect(struct TCP_Server_Info *s
+ rc = generic_ip_connect(server);
+ if (rc) {
+ cifs_dbg(FYI, "reconnect error %d\n", rc);
++ rc = reconn_set_ipaddr(server);
++ if (rc) {
++ cifs_dbg(FYI, "%s: failed to resolve hostname: %d\n",
++ __func__, rc);
++ }
+ mutex_unlock(&server->srv_mutex);
+ msleep(3000);
+ } else {
--- /dev/null
+From 726e41097920a73e4c7c33385dcc0debb1281e18 Mon Sep 17 00:00:00 2001
+From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
+Date: Tue, 10 Jul 2018 10:29:10 +1000
+Subject: drivers: core: Remove glue dirs from sysfs earlier
+
+From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
+
+commit 726e41097920a73e4c7c33385dcc0debb1281e18 upstream.
+
+For devices with a class, we create a "glue" directory between
+the parent device and the new device with the class name.
+
+This directory is never "explicitely" removed when empty however,
+this is left to the implicit sysfs removal done by kobject_release()
+when the object loses its last reference via kobject_put().
+
+This is problematic because as long as it's not been removed from
+sysfs, it is still present in the class kset and in sysfs directory
+structure.
+
+The presence in the class kset exposes a use after free bug fixed
+by the previous patch, but the presence in sysfs means that until
+the kobject is released, which can take a while (especially with
+kobject debugging), any attempt at re-creating such as binding a
+new device for that class/parent pair, will result in a sysfs
+duplicate file name error.
+
+This fixes it by instead doing an explicit kobject_del() when
+the glue dir is empty, by keeping track of the number of
+child devices of the gluedir.
+
+This is made easy by the fact that all glue dir operations are
+done with a global mutex, and there's already a function
+(cleanup_glue_dir) called in all the right places taking that
+mutex that can be enhanced for this. It appears that this was
+in fact the intent of the function, but the implementation was
+wrong.
+
+Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
+Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Zubin Mithra <zsm@chromium.org>
+Cc: Guenter Roeck <groeck@google.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/base/core.c | 2 ++
+ include/linux/kobject.h | 17 +++++++++++++++++
+ 2 files changed, 19 insertions(+)
+
+--- a/drivers/base/core.c
++++ b/drivers/base/core.c
+@@ -862,6 +862,8 @@ static void cleanup_glue_dir(struct devi
+ return;
+
+ mutex_lock(&gdp_mutex);
++ if (!kobject_has_children(glue_dir))
++ kobject_del(glue_dir);
+ kobject_put(glue_dir);
+ mutex_unlock(&gdp_mutex);
+ }
+--- a/include/linux/kobject.h
++++ b/include/linux/kobject.h
+@@ -113,6 +113,23 @@ extern void kobject_put(struct kobject *
+ extern const void *kobject_namespace(struct kobject *kobj);
+ extern char *kobject_get_path(struct kobject *kobj, gfp_t flag);
+
++/**
++ * kobject_has_children - Returns whether a kobject has children.
++ * @kobj: the object to test
++ *
++ * This will return whether a kobject has other kobjects as children.
++ *
++ * It does NOT account for the presence of attribute files, only sub
++ * directories. It also assumes there is no concurrent addition or
++ * removal of such children, and thus relies on external locking.
++ */
++static inline bool kobject_has_children(struct kobject *kobj)
++{
++ WARN_ON_ONCE(atomic_read(&kobj->kref.refcount) == 0);
++
++ return kobj->sd && kobj->sd->dir.subdirs;
++}
++
+ struct kobj_type {
+ void (*release)(struct kobject *kobj);
+ const struct sysfs_ops *sysfs_ops;
projects / thirdparty / kernel / stable-queue.git / commitdiff
