From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Fri, 28 Jun 2019 11:03:41 -0700
Subject: idr: fix overflow case for idr_for_each_entry_ul()
Patch-mainline: v5.3-rc1
Git-commit: e33d2b74d805af0e4c8060f41040595ba105a520
References: bsc#1109837

idr_for_each_entry_ul() is buggy as it can't handle overflow
case correctly. When we have an ID == UINT_MAX, it becomes an
infinite loop. This happens when running on 32-bit CPU where
unsigned long has the same size with unsigned int.

There is no better way to fix this than casting it to a larger
integer, but we can't just 64 bit integer on 32 bit CPU. Instead
we could just use an additional integer to help us to detect this
overflow case, that is, adding a new parameter to this macro.
Fortunately tc action is its only user right now.

Fixes: 65a206c01e8e ("net/sched: Change act_api and act_xxx modules to use IDR")
Reported-by: Li Shuang <shuali@redhat.com>
Tested-by: Davide Caratti <dcaratti@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Chris Mi <chrism@mellanox.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 include/linux/idr.h |    7 +++++--
 net/sched/act_api.c |    9 ++++++---
 2 files changed, 11 insertions(+), 5 deletions(-)

--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -156,14 +156,17 @@ static inline void *idr_find(const struc
  * idr_for_each_entry_ul() - Iterate over an IDR's elements of a given type.
  * @idr: IDR handle.
  * @entry: The type * to use as cursor.
+ * @tmp: A temporary placeholder for ID.
  * @id: Entry ID.
  *
  * @entry and @id do not need to be initialized before the loop, and
  * after normal termination @entry is left with the value NULL.  This
  * is convenient for a "not found" value.
  */
-#define idr_for_each_entry_ul(idr, entry, id)			\
-	for (id = 0; ((entry) = idr_get_next_ul(idr, &(id))) != NULL; ++id)
+#define idr_for_each_entry_ul(idr, entry, tmp, id)			\
+	for (tmp = 0, id = 0;						\
+	     tmp <= id && ((entry) = idr_get_next_ul(idr, &(id))) != NULL; \
+	     tmp = id, ++id)
 
 /**
  * idr_for_each_entry_continue() - Continue iteration over an IDR's elements of a given type
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -199,12 +199,13 @@ static int tcf_dump_walker(struct tcf_id
 	struct idr *idr = &idrinfo->action_idr;
 	struct tc_action *p;
 	unsigned long id = 1;
+	unsigned long tmp;
 
 	mutex_lock(&idrinfo->lock);
 
 	s_i = cb->args[0];
 
-	idr_for_each_entry_ul(idr, p, id) {
+	idr_for_each_entry_ul(idr, p, tmp, id) {
 		index++;
 		if (index < s_i)
 			continue;
@@ -270,6 +271,7 @@ static int tcf_del_walker(struct tcf_idr
 	struct idr *idr = &idrinfo->action_idr;
 	struct tc_action *p;
 	unsigned long id = 1;
+	unsigned long tmp;
 
 	nest = nla_nest_start(skb, 0);
 	if (nest == NULL)
@@ -278,7 +280,7 @@ static int tcf_del_walker(struct tcf_idr
 		goto nla_put_failure;
 
 	mutex_lock(&idrinfo->lock);
-	idr_for_each_entry_ul(idr, p, id) {
+	idr_for_each_entry_ul(idr, p, tmp, id) {
 		ret = tcf_idr_release_unsafe(p);
 		if (ret == ACT_P_DELETED) {
 			module_put(ops->owner);
@@ -511,8 +513,9 @@ void tcf_idrinfo_destroy(const struct tc
 	struct tc_action *p;
 	int ret;
 	unsigned long id = 1;
+	unsigned long tmp;
 
-	idr_for_each_entry_ul(idr, p, id) {
+	idr_for_each_entry_ul(idr, p, tmp, id) {
 		ret = __tcf_idr_release(p, false, true);
 		if (ret == ACT_P_DELETED)
 			module_put(ops->owner);