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appletalk: Fix potential NULL pointer dereference in unregister_snap_client 

register_snap_client may return NULL, all the callers
check it, but only print a warning. This will result in
NULL pointer dereference in unregister_snap_client and other
places.

It has always been used like this since v2.6

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
YueHaibing 2019-03-14 13:47:59 +08:00 committed by David S. Miller
parent f261c4e529
commit 9804501fa1
3 changed files with 25 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/atalk.h
View File

@ -108,7 +108,7 @@ static __inline__ struct elapaarp *aarp_hdr(struct sk_buff *skb)
#define AARP_RESOLVE_TIME (10 * HZ)
extern struct datalink_proto *ddp_dl, *aarp_dl;
extern void aarp_proto_init(void);
extern int aarp_proto_init(void);
/* Inter module exports */

15
net/appletalk/aarp.c
View File

@ -879,15 +879,24 @@ static struct notifier_block aarp_notifier = {
static unsigned char aarp_snap_id[] = { 0x00, 0x00, 0x00, 0x80, 0xF3 };
void __init aarp_proto_init(void)
int __init aarp_proto_init(void)
{
int rc;
aarp_dl = register_snap_client(aarp_snap_id, aarp_rcv);
if (!aarp_dl)
if (!aarp_dl) {
printk(KERN_CRIT "Unable to register AARP with SNAP.\n");
return -ENOMEM;
}
timer_setup(&aarp_timer, aarp_expire_timeout, 0);
aarp_timer.expires = jiffies + sysctl_aarp_expiry_time;
add_timer(&aarp_timer);
register_netdevice_notifier(&aarp_notifier);
rc = register_netdevice_notifier(&aarp_notifier);
if (rc) {
del_timer_sync(&aarp_timer);
unregister_snap_client(aarp_dl);
}
return rc;
}
/* Remove the AARP entries associated with a device. */

20
net/appletalk/ddp.c
View File

@ -1904,9 +1904,6 @@ static unsigned char ddp_snap_id[] = { 0x08, 0x00, 0x07, 0x80, 0x9B };
EXPORT_SYMBOL(atrtr_get_dev);
EXPORT_SYMBOL(atalk_find_dev_addr);
static const char atalk_err_snap[] __initconst =
KERN_CRIT "Unable to register DDP with SNAP.\n";
/* Called by proto.c on kernel start up */
static int __init atalk_init(void)
{
@ -1921,17 +1918,22 @@ static int __init atalk_init(void)
goto out_proto;
ddp_dl = register_snap_client(ddp_snap_id, atalk_rcv);
if (!ddp_dl)
printk(atalk_err_snap);
if (!ddp_dl) {
pr_crit("Unable to register DDP with SNAP.\n");
goto out_sock;
}
dev_add_pack(&ltalk_packet_type);
dev_add_pack(&ppptalk_packet_type);
rc = register_netdevice_notifier(&ddp_notifier);
if (rc)
goto out_sock;
goto out_snap;
rc = aarp_proto_init();
if (rc)
goto out_dev;
aarp_proto_init();
rc = atalk_proc_init();
if (rc)
goto out_aarp;
@ -1945,11 +1947,13 @@ static int __init atalk_init(void)
atalk_proc_exit();
out_aarp:
aarp_cleanup_module();
out_dev:
unregister_netdevice_notifier(&ddp_notifier);
out_sock:
out_snap:
dev_remove_pack(&ppptalk_packet_type);
dev_remove_pack(&ltalk_packet_type);
unregister_snap_client(ddp_dl);
out_sock:
sock_unregister(PF_APPLETALK);
out_proto:
proto_unregister(&ddp_proto);