[PATCH 2/2] hwtracing: stm: fix double-free in stm_source_register_device()

From: Kefeng Wang
Date: Mon May 20 2019 - 05:07:03 EST


If device_add() in stm_source_register_device() fails,
stm_source_device_release() is called to free src, free
src again on err path will trigger double free issue.

BUG: KASAN: double-free or invalid-free in stm_source_register_device+0xd0/0x1a0 [stm_core]

CPU: 1 PID: 8556 Comm: syz-executor.0 Tainted: G C 5.1.0+ #28
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:188
kasan_report_invalid_free+0x60/0xa0 mm/kasan/report.c:279
__kasan_slab_free+0x159/0x180 mm/kasan/common.c:430
slab_free_hook mm/slub.c:1420 [inline]
slab_free_freelist_hook mm/slub.c:1447 [inline]
slab_free mm/slub.c:2994 [inline]
kfree+0xe1/0x270 mm/slub.c:3949
stm_source_register_device+0xd0/0x1a0 [stm_core]
stm_heartbeat_init+0xb6/0x1b0 [stm_heartbeat]
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

...

Allocated by task 8556:
save_stack+0x19/0x80 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_kmalloc.constprop.2+0xa0/0xd0 mm/kasan/common.c:489
stm_source_register_device+0x46/0x1a0 [stm_core]
stm_heartbeat_init+0xb6/0x1b0 [stm_heartbeat]
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

Freed by task 8556:
save_stack+0x19/0x80 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_slab_free+0x130/0x180 mm/kasan/common.c:451
slab_free_hook mm/slub.c:1420 [inline]
slab_free_freelist_hook mm/slub.c:1447 [inline]
slab_free mm/slub.c:2994 [inline]
kfree+0xe1/0x270 mm/slub.c:3949
device_release+0x46/0x100 drivers/base/core.c:1064
kobject_cleanup lib/kobject.c:691 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:67 [inline]
kobject_put+0x1a8/0x220 lib/kobject.c:737
put_device+0x1b/0x30 drivers/base/core.c:2210
stm_source_register_device+0xc8/0x1a0 [stm_core]
stm_heartbeat_init+0xb6/0x1b0 [stm_heartbeat]
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

Don't call kfree(src) if device_add() fails to fix it.

Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
---
drivers/hwtracing/stm/core.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index 7b2ab7b2cc4d..5ce30f8f8c4f 100644
--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -1258,15 +1258,20 @@ int stm_source_register_device(struct device *parent,
src->dev.release = stm_source_device_release;

err = kobject_set_name(&src->dev.kobj, "%s", data->name);
- if (err)
+ if (err) {
+ put_device(&src->dev);
+ kfree(src);
goto err;
+ }

pm_runtime_no_callbacks(&src->dev);
pm_runtime_forbid(&src->dev);

err = device_add(&src->dev);
- if (err)
- goto err;
+ if (err) {
+ put_device(&src->dev);
+ return err;
+ }

stm_output_init(&src->output);
spin_lock_init(&src->link_lock);
@@ -1275,12 +1280,6 @@ int stm_source_register_device(struct device *parent,
data->src = src;

return 0;
-
-err:
- put_device(&src->dev);
- kfree(src);
-
- return err;
}
EXPORT_SYMBOL_GPL(stm_source_register_device);

--
2.20.1