[PATCH 3.18 083/104] appletalk: Fix use-after-free in atalk_proc_exit

Greg Kroah-Hartman
2019-04-24T17:15:42Z

[ Upstream commit 6377f787aeb945cae7abbb6474798de129e1f3ac ]

KASAN report this:

BUG: KASAN: use-after-free in pde_subdir_find+0x12d/0x150 fs/proc/generic.c:71
Read of size 8 at addr ffff8881f41fe5b0 by task syz-executor.0/2806

CPU: 0 PID: 2806 Comm: syz-executor.0 Not tainted 5.0.0-rc7+ #45
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0xfa/0x1ce lib/dump_stack.c:113
print_address_description+0x65/0x270 mm/kasan/report.c:187
kasan_report+0x149/0x18d mm/kasan/report.c:317
pde_subdir_find+0x12d/0x150 fs/proc/generic.c:71
remove_proc_entry+0xe8/0x420 fs/proc/generic.c:667
atalk_proc_exit+0x18/0x820 [appletalk]
atalk_exit+0xf/0x5a [appletalk]
__do_sys_delete_module kernel/module.c:1018 [inline]
__se_sys_delete_module kernel/module.c:961 [inline]
__x64_sys_delete_module+0x3dc/0x5e0 kernel/module.c:961
do_syscall_64+0x147/0x600 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x462e99
Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb2de6b9c58 EFLAGS: 00000246 ORIG_RAX: 00000000000000b0
RAX: ffffffffffffffda RBX: 000000000073bf00 RCX: 0000000000462e99
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000200001c0
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb2de6ba6bc
R13: 00000000004bccaa R14: 00000000006f6bc8 R15: 00000000ffffffff

Allocated by task 2806:
set_track mm/kasan/common.c:85 [inline]
__kasan_kmalloc.constprop.3+0xa0/0xd0 mm/kasan/common.c:496
slab_post_alloc_hook mm/slab.h:444 [inline]
slab_alloc_node mm/slub.c:2739 [inline]
slab_alloc mm/slub.c:2747 [inline]
kmem_cache_alloc+0xcf/0x250 mm/slub.c:2752
kmem_cache_zalloc include/linux/slab.h:730 [inline]
__proc_create+0x30f/0xa20 fs/proc/generic.c:408
proc_mkdir_data+0x47/0x190 fs/proc/generic.c:469
0xffffffffc10c01bb
0xffffffffc10c0166
do_one_initcall+0xfa/0x5ca init/main.c:887
do_init_module+0x204/0x5f6 kernel/module.c:3460
load_module+0x66b2/0x8570 kernel/module.c:3808
__do_sys_finit_module+0x238/0x2a0 kernel/module.c:3902
do_syscall_64+0x147/0x600 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 2806:
set_track mm/kasan/common.c:85 [inline]
__kasan_slab_free+0x130/0x180 mm/kasan/common.c:458
slab_free_hook mm/slub.c:1409 [inline]
slab_free_freelist_hook mm/slub.c:1436 [inline]
slab_free mm/slub.c:2986 [inline]
kmem_cache_free+0xa6/0x2a0 mm/slub.c:3002
pde_put+0x6e/0x80 fs/proc/generic.c:647
remove_proc_entry+0x1d3/0x420 fs/proc/generic.c:684
0xffffffffc10c031c
0xffffffffc10c0166
do_one_initcall+0xfa/0x5ca init/main.c:887
do_init_module+0x204/0x5f6 kernel/module.c:3460
load_module+0x66b2/0x8570 kernel/module.c:3808
__do_sys_finit_module+0x238/0x2a0 kernel/module.c:3902
do_syscall_64+0x147/0x600 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8881f41fe500
which belongs to the cache proc_dir_entry of size 256
The buggy address is located 176 bytes inside of
256-byte region [ffff8881f41fe500, ffff8881f41fe600)
The buggy address belongs to the page:
page:ffffea0007d07f80 count:1 mapcount:0 mapping:ffff8881f6e69a00 index:0x0
flags: 0x2fffc0000000200(slab)
raw: 02fffc0000000200 dead000000000100 dead000000000200 ffff8881f6e69a00
raw: 0000000000000000 00000000800c000c 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8881f41fe480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff8881f41fe500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881f41fe580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8881f41fe600: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ffff8881f41fe680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

It should check the return value of atalk_proc_init fails,
otherwise atalk_exit will trgger use-after-free in pde_subdir_find
while unload the module.This patch fix error cleanup path of atalk_init

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/atalk.h | 2 +-
net/appletalk/atalk_proc.c | 2 +-
net/appletalk/ddp.c | 37 ++++++++++++++++++++++++++------
net/appletalk/sysctl_net_atalk.c | 5 ++++-
4 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/include/linux/atalk.h b/include/linux/atalk.h
index 73fd8b7e9534..716d53799d1f 100644
--- a/include/linux/atalk.h
+++ b/include/linux/atalk.h
@@ -150,7 +150,7 @@ extern int sysctl_aarp_retransmit_limit;
extern int sysctl_aarp_resolve_time;

#ifdef CONFIG_SYSCTL
-extern void atalk_register_sysctl(void);
+extern int atalk_register_sysctl(void);
extern void atalk_unregister_sysctl(void);
#else
#define atalk_register_sysctl() do { } while(0)
diff --git a/net/appletalk/atalk_proc.c b/net/appletalk/atalk_proc.c
index af46bc49e1e9..b5f84f428aa6 100644
--- a/net/appletalk/atalk_proc.c
+++ b/net/appletalk/atalk_proc.c
@@ -293,7 +293,7 @@ int __init atalk_proc_init(void)
goto out;
}

-void __exit atalk_proc_exit(void)
+void atalk_proc_exit(void)
{
remove_proc_entry("interface", atalk_proc_dir);
remove_proc_entry("route", atalk_proc_dir);
diff --git a/net/appletalk/ddp.c b/net/appletalk/ddp.c
index c00897f65a31..276a09d7c537 100644
--- a/net/appletalk/ddp.c
+++ b/net/appletalk/ddp.c
@@ -1913,12 +1913,16 @@ static const char atalk_err_snap[] __initconst =
/* Called by proto.c on kernel start up */
static int __init atalk_init(void)
{
- int rc = proto_register(&ddp_proto, 0);
+ int rc;

- if (rc != 0)
+ rc = proto_register(&ddp_proto, 0);
+ if (rc)
goto out;

- (void)sock_register(&atalk_family_ops);
+ rc = sock_register(&atalk_family_ops);
+ if (rc)
+ goto out_proto;
+
ddp_dl = register_snap_client(ddp_snap_id, atalk_rcv);
if (!ddp_dl)
printk(atalk_err_snap);
@@ -1926,12 +1930,33 @@ static int __init atalk_init(void)
dev_add_pack(&ltalk_packet_type);
dev_add_pack(&ppptalk_packet_type);

- register_netdevice_notifier(&ddp_notifier);
+ rc = register_netdevice_notifier(&ddp_notifier);
+ if (rc)
+ goto out_sock;
+
aarp_proto_init();
- atalk_proc_init();
- atalk_register_sysctl();
+ rc = atalk_proc_init();
+ if (rc)
+ goto out_aarp;
+
+ rc = atalk_register_sysctl();
+ if (rc)
+ goto out_proc;
out:
return rc;
+out_proc:
+ atalk_proc_exit();
+out_aarp:
+ aarp_cleanup_module();
+ unregister_netdevice_notifier(&ddp_notifier);
+out_sock:
+ dev_remove_pack(&ppptalk_packet_type);
+ dev_remove_pack(&ltalk_packet_type);
+ unregister_snap_client(ddp_dl);
+ sock_unregister(PF_APPLETALK);
+out_proto:
+ proto_unregister(&ddp_proto);
+ goto out;
}
module_init(atalk_init);

diff --git a/net/appletalk/sysctl_net_atalk.c b/net/appletalk/sysctl_net_atalk.c
index ebb864361f7a..4e6042e0fcac 100644
--- a/net/appletalk/sysctl_net_atalk.c
+++ b/net/appletalk/sysctl_net_atalk.c
@@ -44,9 +44,12 @@ static struct ctl_table atalk_table[] = {

static struct ctl_table_header *atalk_table_header;

-void atalk_register_sysctl(void)
+int __init atalk_register_sysctl(void)
{
atalk_table_header = register_net_sysctl(&init_net, "net/appletalk", atalk_table);
+ if (!atalk_table_header)
+ return -ENOMEM;
+ return 0;
}

void atalk_unregister_sysctl(void)
--
2.19.1