[PATCH v2] appletalk: Fix use-after-free in atalk_proc_exit

[PATCH v2] appletalk: Fix use-after-free in atalk_proc_exit

[Yue Haibing]

From: YueHaibing <yuehaibing@huawei.com>

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,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>
---
v2: fix error cleanup path of atalk_init
---
 include/linux/atalk.h            |  2 +-
 net/appletalk/ddp.c              | 37 +++++++++++++++++++++++++++++++------
 net/appletalk/sysctl_net_atalk.c |  5 ++++-
 3 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/include/linux/atalk.h b/include/linux/atalk.h
index 23f8055..5a90f28 100644
--- a/include/linux/atalk.h
+++ b/include/linux/atalk.h
@@ -158,7 +158,7 @@ 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/ddp.c b/net/appletalk/ddp.c
index 9b6bc5a..795fbc6 100644
--- a/net/appletalk/ddp.c
+++ b/net/appletalk/ddp.c
@@ -1910,12 +1910,16 @@ 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);
@@ -1923,12 +1927,33 @@ 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 c744a85..d945b7c 100644
--- a/net/appletalk/sysctl_net_atalk.c
+++ b/net/appletalk/sysctl_net_atalk.c
@@ -45,9 +45,12 @@ 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)
-- 
2.7.0

Re: [PATCH v2] appletalk: Fix use-after-free in atalk_proc_exit

[kbuild test robot]

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Hi YueHaibing,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net-next/master]
[also build test WARNING on v5.0-rc8 next-20190228]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Yue-Haibing/appletalk-Fix-use-after-free-in-atalk_proc_exit/20190228-195802
config: i386-randconfig-x003-201908 (attached as .config)
compiler: gcc-8 (Debian 8.2.0-20) 8.2.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All warnings (new ones prefixed by >>):

>> WARNING: net/appletalk/appletalk.o(.init.text+0x104): Section mismatch in reference from the function init_module() to the function .exit.text:atalk_proc_exit()
   The function __init init_module() references
   a function __exit atalk_proc_exit().
   This is often seen when error handling in the init function
   uses functionality in the exit path.
   The fix is often to remove the __exit annotation of
   atalk_proc_exit() so it may be used outside an exit section.

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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Re: [PATCH v2] appletalk: Fix use-after-free in atalk_proc_exit

[YueHaibing]

On 2019/2/28 20:38, kbuild test robot wrote:
> Hi YueHaibing,
> 
> Thank you for the patch! Perhaps something to improve:
> 
> [auto build test WARNING on net-next/master]
> [also build test WARNING on v5.0-rc8 next-20190228]
> [if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
> 
> url:    https://github.com/0day-ci/linux/commits/Yue-Haibing/appletalk-Fix-use-after-free-in-atalk_proc_exit/20190228-195802
> config: i386-randconfig-x003-201908 (attached as .config)
> compiler: gcc-8 (Debian 8.2.0-20) 8.2.0
> reproduce:
>         # save the attached .config to linux build tree
>         make ARCH=i386 
> 
> All warnings (new ones prefixed by >>):
> 
>>> WARNING: net/appletalk/appletalk.o(.init.text+0x104): Section mismatch in reference from the function init_module() to the function .exit.text:atalk_proc_exit()
>    The function __init init_module() references
>    a function __exit atalk_proc_exit().
>    This is often seen when error handling in the init function
>    uses functionality in the exit path.
>    The fix is often to remove the __exit annotation of
>    atalk_proc_exit() so it may be used outside an exit section.

Thanks, will fix it.

> 
> ---
> 0-DAY kernel test infrastructure                Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
> 

Re: [PATCH v2] appletalk: Fix use-after-free in atalk_proc_exit

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1417 bytes --]

Hi YueHaibing,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net-next/master]
[also build test WARNING on v5.0-rc8 next-20190228]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Yue-Haibing/appletalk-Fix-use-after-free-in-atalk_proc_exit/20190228-195802
config: arm64-allyesconfig (attached as .config)
compiler: aarch64-linux-gnu-gcc (Debian 8.2.0-11) 8.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=8.2.0 make.cross ARCH=arm64 

All warnings (new ones prefixed by >>):

>> WARNING: vmlinux.o(.init.text+0x1ebba4): Section mismatch in reference from the function atalk_init() to the function .exit.text:atalk_proc_exit()
   The function __init atalk_init() references
   a function __exit atalk_proc_exit().
   This is often seen when error handling in the init function
   uses functionality in the exit path.
   The fix is often to remove the __exit annotation of
   atalk_proc_exit() so it may be used outside an exit section.

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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