[patch 07/26] Fix ROSE module unload oops.

[Greg KH <gregkh@suse.de>]

2.6.22-stable review patch.  If anyone has any objections, please let us
know.

------------------
From: Alexey Dobriyan <adobriyan@gmail.com>

changeset 891e6a931255238dddd08a7b306871240961a27f from mainline.

Commit a3d384029aa304f8f3f5355d35f0ae274454f7cd aka
"[AX.25]: Fix unchecked rose_add_loopback_neigh uses"
transformed rose_loopback_neigh var into statically allocated one.
However, on unload it will be kfree's which can't work.

Steps to reproduce:

	modprobe rose
	rmmod rose

BUG: unable to handle kernel NULL pointer dereference at virtual address 00000008
 printing eip:
c014c664
*pde = 00000000
Oops: 0000 [#1]
PREEMPT DEBUG_PAGEALLOC
Modules linked in: rose ax25 fan ufs loop usbhid rtc snd_intel8x0 snd_ac97_codec ehci_hcd ac97_bus uhci_hcd thermal usbcore button processor evdev sr_mod cdrom
CPU:    0
EIP:    0060:[<c014c664>]    Not tainted VLI
EFLAGS: 00210086   (2.6.23-rc9 #3)
EIP is at kfree+0x48/0xa1
eax: 00000556   ebx: c1734aa0   ecx: f6a5e000   edx: f7082000
esi: 00000000   edi: f9a55d20   ebp: 00200287   esp: f6a5ef28
ds: 007b   es: 007b   fs: 0000  gs: 0033  ss: 0068
Process rmmod (pid: 1823, ti=f6a5e000 task=f7082000 task.ti=f6a5e000)
Stack: f9a55d20 f9a5200c 00000000 00000000 00000000 f6a5e000 f9a5200c f9a55a00
       00000000 bf818cf0 f9a51f3f f9a55a00 00000000 c0132c60 65736f72 00000000
       f69f9630 f69f9528 c014244a f6a4e900 00200246 f7082000 c01025e6 00000000
Call Trace:
 [<f9a5200c>] rose_rt_free+0x1d/0x49 [rose]
 [<f9a5200c>] rose_rt_free+0x1d/0x49 [rose]
 [<f9a51f3f>] rose_exit+0x4c/0xd5 [rose]
 [<c0132c60>] sys_delete_module+0x15e/0x186
 [<c014244a>] remove_vma+0x40/0x45
 [<c01025e6>] sysenter_past_esp+0x8f/0x99
 [<c012bacf>] trace_hardirqs_on+0x118/0x13b
 [<c01025b6>] sysenter_past_esp+0x5f/0x99
 =======================
Code: 05 03 1d 80 db 5b c0 8b 03 25 00 40 02 00 3d 00 40 02 00 75 03 8b 5b 0c 8b 73 10 8b 44 24 18 89 44 24 04 9c 5d fa e8 77 df fd ff <8b> 56 08 89 f8 e8 84 f4 fd ff e8 bd 32 06 00 3b 5c 86 60 75 0f
EIP: [<c014c664>] kfree+0x48/0xa1 SS:ESP 0068:f6a5ef28

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 include/net/rose.h       |    2 +-
 net/rose/rose_loopback.c |    4 ++--
 net/rose/rose_route.c    |   15 ++++++++++-----
 3 files changed, 13 insertions(+), 8 deletions(-)

--- a/include/net/rose.h
+++ b/include/net/rose.h
@@ -188,7 +188,7 @@ extern void rose_kick(struct sock *);
 extern void rose_enquiry_response(struct sock *);
 
 /* rose_route.c */
-extern struct rose_neigh rose_loopback_neigh;
+extern struct rose_neigh *rose_loopback_neigh;
 extern const struct file_operations rose_neigh_fops;
 extern const struct file_operations rose_nodes_fops;
 extern const struct file_operations rose_routes_fops;
--- a/net/rose/rose_loopback.c
+++ b/net/rose/rose_loopback.c
@@ -79,7 +79,7 @@ static void rose_loopback_timer(unsigned
 
 		skb_reset_transport_header(skb);
 
-		sk = rose_find_socket(lci_o, &rose_loopback_neigh);
+		sk = rose_find_socket(lci_o, rose_loopback_neigh);
 		if (sk) {
 			if (rose_process_rx_frame(sk, skb) == 0)
 				kfree_skb(skb);
@@ -88,7 +88,7 @@ static void rose_loopback_timer(unsigned
 
 		if (frametype == ROSE_CALL_REQUEST) {
 			if ((dev = rose_dev_get(dest)) != NULL) {
-				if (rose_rx_call_request(skb, dev, &rose_loopback_neigh, lci_o) == 0)
+				if (rose_rx_call_request(skb, dev, rose_loopback_neigh, lci_o) == 0)
 					kfree_skb(skb);
 			} else {
 				kfree_skb(skb);
--- a/net/rose/rose_route.c
+++ b/net/rose/rose_route.c
@@ -45,7 +45,7 @@ static DEFINE_SPINLOCK(rose_neigh_list_l
 static struct rose_route *rose_route_list;
 static DEFINE_SPINLOCK(rose_route_list_lock);
 
-struct rose_neigh rose_loopback_neigh;
+struct rose_neigh *rose_loopback_neigh;
 
 /*
  *	Add a new route to a node, and in the process add the node and the
@@ -362,7 +362,12 @@ out:
  */
 void rose_add_loopback_neigh(void)
 {
-	struct rose_neigh *sn = &rose_loopback_neigh;
+	struct rose_neigh *sn;
+
+	rose_loopback_neigh = kmalloc(sizeof(struct rose_neigh), GFP_KERNEL);
+	if (!rose_loopback_neigh)
+		return;
+	sn = rose_loopback_neigh;
 
 	sn->callsign  = null_ax25_address;
 	sn->digipeat  = NULL;
@@ -417,13 +422,13 @@ int rose_add_loopback_node(rose_address 
 	rose_node->mask         = 10;
 	rose_node->count        = 1;
 	rose_node->loopback     = 1;
-	rose_node->neighbour[0] = &rose_loopback_neigh;
+	rose_node->neighbour[0] = rose_loopback_neigh;
 
 	/* Insert at the head of list. Address is always mask=10 */
 	rose_node->next = rose_node_list;
 	rose_node_list  = rose_node;
 
-	rose_loopback_neigh.count++;
+	rose_loopback_neigh->count++;
 
 out:
 	spin_unlock_bh(&rose_node_list_lock);
@@ -454,7 +459,7 @@ void rose_del_loopback_node(rose_address
 
 	rose_remove_node(rose_node);
 
-	rose_loopback_neigh.count--;
+	rose_loopback_neigh->count--;
 
 out:
 	spin_unlock_bh(&rose_node_list_lock);

-- 
-
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