[PATCH] stm class: fix possible double-free in stm_source_register_device()

[Wang Hai]

Syzkaller report this:

BUG: KASAN: double-free or invalid-free in stm_source_register_device+0x137/0x2b0 [stm_core]

CPU: 1 PID: 6763 Comm: syz-executor.0 Tainted: G         C        5.0.0+ #5
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+0xa9/0x10e lib/dump_stack.c:113
 print_address_description+0x65/0x270 mm/kasan/report.c:187
 kasan_report_invalid_free+0x60/0xa0 mm/kasan/report.c:278
 __kasan_slab_free+0x159/0x180 mm/kasan/common.c:438
 slab_free_hook mm/slub.c:1429 [inline]
 slab_free_freelist_hook mm/slub.c:1456 [inline]
 slab_free mm/slub.c:3003 [inline]
 kfree+0xe1/0x270 mm/slub.c:3955
 stm_source_register_device+0x137/0x2b0 [stm_core]
 do_one_initcall+0xbc/0x47d init/main.c:887
 do_init_module+0x1b5/0x547 kernel/module.c:3456
 load_module+0x6405/0x8c10 kernel/module.c:3804
 __do_sys_finit_module+0x162/0x190 kernel/module.c:3898
 do_syscall_64+0x9f/0x450 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Allocated by task 6763:
 set_track mm/kasan/common.c:87 [inline]
 __kasan_kmalloc.constprop.3+0xa0/0xd0 mm/kasan/common.c:497
 stm_source_register_device+0x5c/0x2b0 [stm_core]
 do_one_initcall+0xbc/0x47d init/main.c:887
 do_init_module+0x1b5/0x547 kernel/module.c:3456
 load_module+0x6405/0x8c10 kernel/module.c:3804
 __do_sys_finit_module+0x162/0x190 kernel/module.c:3898
 do_syscall_64+0x9f/0x450 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 6763:
 set_track mm/kasan/common.c:87 [inline]
 __kasan_slab_free+0x130/0x180 mm/kasan/common.c:459
 slab_free_hook mm/slub.c:1429 [inline]
 slab_free_freelist_hook mm/slub.c:1456 [inline]
 slab_free mm/slub.c:3003 [inline]
 kfree+0xe1/0x270 mm/slub.c:3955
 device_release+0x78/0x200 drivers/base/core.c:1064
 kobject_cleanup lib/kobject.c:662 [inline]
 kobject_release lib/kobject.c:691 [inline]
 kref_put include/linux/kref.h:67 [inline]
 kobject_put+0x2a8/0x400 lib/kobject.c:708
 put_device+0x1c/0x30 drivers/base/core.c:2205
 stm_source_register_device+0x12f/0x2b0 [stm_core]
 do_one_initcall+0xbc/0x47d init/main.c:887
 do_init_module+0x1b5/0x547 kernel/module.c:3456
 load_module+0x6405/0x8c10 kernel/module.c:3804
 __do_sys_finit_module+0x162/0x190 kernel/module.c:3898
 do_syscall_64+0x9f/0x450 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

int stm_source_register_device(){
	...
    src->dev.release = stm_source_device_release;
	...
    err:
         put_device(&src->dev);
         kfree(src);

         return err;
}
In the error handling path of stm_source_register_device
Put_device() causes stm_source_device_release->kfree(src) to be
called. So calling kfree(src) again will cause double free

Fixes: 7bd1d4093c2f ("stm class: Introduce an abstraction for System Trace Module devices")
Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Signed-off-by: Wang Hai <wanghai26@xxxxxxxxxx>
---
 drivers/hwtracing/stm/core.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index e55b902560de..181e7ff1ec4f 100644
--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -1276,7 +1276,6 @@ int stm_source_register_device(struct device *parent,
 
 err:
 	put_device(&src->dev);
-	kfree(src);
 
 	return err;
 }
-- 
2.17.1