Re: [linus:master] [sysctl] 8d75c338f0: BUG:KASAN:slab-use-after-free_in_touch_wq_lockdep_map

[Oleg Nesterov]

On 10/19, Oleg Nesterov wrote:
>
> But. rds_init() can also fail even if CONFIG_SYSCTL=y, after
> rds_sysctl_init(), so to me this looks like a bug in net/rds/.
>
>
> In any case, I guess net/rds/ init paths should not fail if
> CONFIG_SYSCTL=n ?

So I think that something like the uncompiled/untested patch below makes
sense anyway even if doesn't fix all the potential problems with rds_wq.

What do you think?

Oleg.
---

diff --git a/net/rds/ib_sysctl.c b/net/rds/ib_sysctl.c
index 2af678e71e3c..bccdb5c4df1d 100644
--- a/net/rds/ib_sysctl.c
+++ b/net/rds/ib_sysctl.c
@@ -36,19 +36,10 @@
 
 #include "ib.h"
 
-static struct ctl_table_header *rds_ib_sysctl_hdr;
-
 unsigned long rds_ib_sysctl_max_send_wr = RDS_IB_DEFAULT_SEND_WR;
 unsigned long rds_ib_sysctl_max_recv_wr = RDS_IB_DEFAULT_RECV_WR;
 unsigned long rds_ib_sysctl_max_recv_allocation = (128 * 1024 * 1024) / RDS_FRAG_SIZE;
-static unsigned long rds_ib_sysctl_max_wr_min = 1;
-/* hardware will fail CQ creation long before this */
-static unsigned long rds_ib_sysctl_max_wr_max = (u32)~0;
-
 unsigned long rds_ib_sysctl_max_unsig_wrs = 16;
-static unsigned long rds_ib_sysctl_max_unsig_wr_min = 1;
-static unsigned long rds_ib_sysctl_max_unsig_wr_max = 64;
-
 /*
  * This sysctl does nothing.
  *
@@ -61,6 +52,14 @@ static unsigned long rds_ib_sysctl_max_unsig_wr_max = 64;
  */
 unsigned int rds_ib_sysctl_flow_control = 0;
 
+#ifdef CONFIG_SYSCTL
+static unsigned long rds_ib_sysctl_max_wr_min = 1;
+/* hardware will fail CQ creation long before this */
+static unsigned long rds_ib_sysctl_max_wr_max = (u32)~0;
+
+static unsigned long rds_ib_sysctl_max_unsig_wr_min = 1;
+static unsigned long rds_ib_sysctl_max_unsig_wr_max = 64;
+
 static struct ctl_table rds_ib_sysctl_table[] = {
 	{
 		.procname       = "max_send_wr",
@@ -105,6 +104,8 @@ static struct ctl_table rds_ib_sysctl_table[] = {
 	},
 };
 
+static struct ctl_table_header *rds_ib_sysctl_hdr;
+
 void rds_ib_sysctl_exit(void)
 {
 	if (rds_ib_sysctl_hdr)
@@ -118,3 +119,15 @@ int rds_ib_sysctl_init(void)
 		return -ENOMEM;
 	return 0;
 }
+
+#else
+
+void rds_ib_sysctl_exit(void)
+{
+}
+
+int rds_ib_sysctl_init(void)
+{
+	return 0;
+}
+#endif
diff --git a/net/rds/sysctl.c b/net/rds/sysctl.c
index 025f518a4349..a0673a41633a 100644
--- a/net/rds/sysctl.c
+++ b/net/rds/sysctl.c
@@ -36,11 +36,6 @@
 
 #include "rds.h"
 
-static struct ctl_table_header *rds_sysctl_reg_table;
-
-static unsigned long rds_sysctl_reconnect_min = 1;
-static unsigned long rds_sysctl_reconnect_max = ~0UL;
-
 unsigned long rds_sysctl_reconnect_min_jiffies;
 unsigned long rds_sysctl_reconnect_max_jiffies = HZ;
 
@@ -49,6 +44,10 @@ unsigned int  rds_sysctl_max_unacked_bytes = (16 << 20);
 
 unsigned int rds_sysctl_ping_enable = 1;
 
+#ifdef CONFIG_SYSCTL
+static unsigned long rds_sysctl_reconnect_min = 1;
+static unsigned long rds_sysctl_reconnect_max = ~0UL;
+
 static struct ctl_table rds_sysctl_rds_table[] = {
 	{
 		.procname       = "reconnect_min_delay_ms",
@@ -91,6 +90,8 @@ static struct ctl_table rds_sysctl_rds_table[] = {
 	},
 };
 
+static struct ctl_table_header *rds_sysctl_reg_table;
+
 void rds_sysctl_exit(void)
 {
 	unregister_net_sysctl_table(rds_sysctl_reg_table);
@@ -107,3 +108,15 @@ int rds_sysctl_init(void)
 		return -ENOMEM;
 	return 0;
 }
+
+#else
+
+void rds_sysctl_exit(void)
+{
+}
+
+int rds_sysctl_init(void)
+{
+	return 0;
+}
+#endif