[PATCH] memstick: Fix error cleanup path of memstick_init

[PATCH] memstick: Fix error cleanup path of memstick_init

[Wang Hai]

If bus_register fails. On its error handling path, it has cleaned up
what it has done. There is no need to call bus_unregister again.
Otherwise, if bus_unregister is called, issues such as null-ptr-deref
will arise.

Syzkaller report this:

kobject_add_internal failed for memstick (error: -12 parent: bus)
BUG: KASAN: null-ptr-deref in sysfs_remove_file_ns+0x1b/0x40 fs/sysfs/file.c:467
Read of size 8 at addr 0000000000000078 by task syz-executor.0/4460

Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xa9/0x10e lib/dump_stack.c:113
 __kasan_report+0x171/0x18d mm/kasan/report.c:321
 kasan_report+0xe/0x20 mm/kasan/common.c:614
 sysfs_remove_file_ns+0x1b/0x40 fs/sysfs/file.c:467
 sysfs_remove_file include/linux/sysfs.h:519 [inline]
 bus_remove_file+0x6c/0x90 drivers/base/bus.c:145
 remove_probe_files drivers/base/bus.c:599 [inline]
 bus_unregister+0x6e/0x100 drivers/base/bus.c:916 ? 0xffffffffc1590000
 memstick_init+0x7a/0x1000 [memstick]
 do_one_initcall+0xb9/0x3b5 init/main.c:914
 do_init_module+0xe0/0x330 kernel/module.c:3468
 load_module+0x38eb/0x4270 kernel/module.c:3819
 __do_sys_finit_module+0x162/0x190 kernel/module.c:3909
 do_syscall_64+0x72/0x2a0 arch/x86/entry/common.c:298
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Fixes: baf8532a147d ("memstick: initial commit for Sony MemoryStick support")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wang Hai <wanghai26@huawei.com>
---
 drivers/memstick/core/memstick.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/memstick/core/memstick.c b/drivers/memstick/core/memstick.c
index 1246d69ba187..b1564cacd19e 100644
--- a/drivers/memstick/core/memstick.c
+++ b/drivers/memstick/core/memstick.c
@@ -629,13 +629,18 @@ static int __init memstick_init(void)
 		return -ENOMEM;
 
 	rc = bus_register(&memstick_bus_type);
-	if (!rc)
-		rc = class_register(&memstick_host_class);
+	if (rc)
+		goto error_destroy_workqueue;
 
-	if (!rc)
-		return 0;
+	rc = class_register(&memstick_host_class);
+	if (rc)
+		goto error_bus_unregister;
+
+	return 0;
 
+error_bus_unregister:
 	bus_unregister(&memstick_bus_type);
+error_destroy_workqueue:
 	destroy_workqueue(workqueue);
 
 	return rc;
-- 
2.17.1

Re: [PATCH] memstick: Fix error cleanup path of memstick_init

[Ulf Hansson]

On Wed, 15 May 2019 at 16:39, Wang Hai <wanghai26@huawei.com> wrote:
>
> If bus_register fails. On its error handling path, it has cleaned up
> what it has done. There is no need to call bus_unregister again.
> Otherwise, if bus_unregister is called, issues such as null-ptr-deref
> will arise.
>
> Syzkaller report this:
>
> kobject_add_internal failed for memstick (error: -12 parent: bus)
> BUG: KASAN: null-ptr-deref in sysfs_remove_file_ns+0x1b/0x40 fs/sysfs/file.c:467
> Read of size 8 at addr 0000000000000078 by task syz-executor.0/4460
>
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0xa9/0x10e lib/dump_stack.c:113
>  __kasan_report+0x171/0x18d mm/kasan/report.c:321
>  kasan_report+0xe/0x20 mm/kasan/common.c:614
>  sysfs_remove_file_ns+0x1b/0x40 fs/sysfs/file.c:467
>  sysfs_remove_file include/linux/sysfs.h:519 [inline]
>  bus_remove_file+0x6c/0x90 drivers/base/bus.c:145
>  remove_probe_files drivers/base/bus.c:599 [inline]
>  bus_unregister+0x6e/0x100 drivers/base/bus.c:916 ? 0xffffffffc1590000
>  memstick_init+0x7a/0x1000 [memstick]
>  do_one_initcall+0xb9/0x3b5 init/main.c:914
>  do_init_module+0xe0/0x330 kernel/module.c:3468
>  load_module+0x38eb/0x4270 kernel/module.c:3819
>  __do_sys_finit_module+0x162/0x190 kernel/module.c:3909
>  do_syscall_64+0x72/0x2a0 arch/x86/entry/common.c:298
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Fixes: baf8532a147d ("memstick: initial commit for Sony MemoryStick support")
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Wang Hai <wanghai26@huawei.com>

Applied for next, thanks!

Kind regards
Uffe


> ---
>  drivers/memstick/core/memstick.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/memstick/core/memstick.c b/drivers/memstick/core/memstick.c
> index 1246d69ba187..b1564cacd19e 100644
> --- a/drivers/memstick/core/memstick.c
> +++ b/drivers/memstick/core/memstick.c
> @@ -629,13 +629,18 @@ static int __init memstick_init(void)
>                 return -ENOMEM;
>
>         rc = bus_register(&memstick_bus_type);
> -       if (!rc)
> -               rc = class_register(&memstick_host_class);
> +       if (rc)
> +               goto error_destroy_workqueue;
>
> -       if (!rc)
> -               return 0;
> +       rc = class_register(&memstick_host_class);
> +       if (rc)
> +               goto error_bus_unregister;
> +
> +       return 0;
>
> +error_bus_unregister:
>         bus_unregister(&memstick_bus_type);
> +error_destroy_workqueue:
>         destroy_workqueue(workqueue);
>
>         return rc;
> --
> 2.17.1
>
>