From 157d7ebdbd7479b271e7b1df744b2dfc6b5816e9 Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@felloff.net>
Date: Sun, 12 May 2019 01:20:21 +0200
Subject: [PATCH] devip: do not lock selftab in ipselftabread(), remove unused
 fields from Ipself

the Ipselftab is designed to not require locking on read
operation. locking the selftab in ipselftabread() risks
deadlock when accessing the user buffer creates a fault.

remove unused fields from the Ipself struct.
---
 sys/src/9/ip/ip.h    | 4 ++--
 sys/src/9/ip/ipifc.c | 6 +-----
 2 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/sys/src/9/ip/ip.h b/sys/src/9/ip/ip.h
index 919dd7de6..676c09fc4 100644
--- a/sys/src/9/ip/ip.h
+++ b/sys/src/9/ip/ip.h
@@ -274,9 +274,9 @@ struct Iplink
 	Ipself	*self;
 	Iplifc	*lifc;
 	Iplink	*selflink;	/* next link for this local address */
-	Iplink	*lifclink;	/* next link for this ifc */
-	ulong	expire;
+	Iplink	*lifclink;	/* next link for this lifc */
 	Iplink	*next;		/* free list */
+	ulong	expire;
 	int	ref;
 };
 
diff --git a/sys/src/9/ip/ipifc.c b/sys/src/9/ip/ipifc.c
index 645e4f1e7..45187583b 100644
--- a/sys/src/9/ip/ipifc.c
+++ b/sys/src/9/ip/ipifc.c
@@ -26,12 +26,10 @@ Medium *media[Maxmedia] = { 0 };
 struct Ipself
 {
 	uchar	a[IPaddrlen];
-	Ipself	*hnext;		/* next address in the hash table */
+	Ipself	*next;		/* next address in the hash table */
 	Iplink	*link;		/* binding twixt Ipself and Ipifc */
 	ulong	expire;
 	uchar	type;		/* type of address */
-	int	ref;
-	Ipself	*next;		/* free list */
 };
 
 struct Ipselftab
@@ -1100,7 +1098,6 @@ ipselftabread(Fs *f, char *cp, ulong offset, int n)
 
 	m = 0;
 	off = offset;
-	qlock(f->self);
 	for(i = 0; i < NHASH && m < n; i++){
 		for(p = f->self->hash[i]; p != nil && m < n; p = p->next){
 			nifc = 0;
@@ -1115,7 +1112,6 @@ ipselftabread(Fs *f, char *cp, ulong offset, int n)
 			}
 		}
 	}
-	qunlock(f->self);
 	return m;
 }