Reply: A null-ptr crash in linux-6.4 usb driver

[柳菁峰]

A null-ptr crash was found in usb driver and it crashed with fault-inject. I have made a patch that simply checks for this null pointer, but I am not sure if this will affect certain functions or logic. I hope you can check it carefully please and the format meets the requirements this time.



The crash info:
general protection fault, probably for non-canonical address 0xdffffc0000000021: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f]
CPU: 0 PID: 4280 Comm: syz-executor.3 Not tainted 6.4.0 #8
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
RIP: 0010:__device_attach+0xa9/0x450
Code: e8 03 42 80 3c 20 00 0f 85 3f 03 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 65 48 49 8d bc 24 08 01 00 00 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 06 0f 8e f8 02 00 00 41 f6 84 24 08 01 00 00
RSP: 0018:ffff888116927b98 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 1ffff11022d24f73 RCX: 0000000000000000
RDX: 0000000000000021 RSI: ffffffff847c3300 RDI: 0000000000000108
RBP: ffff88811959b078 R08: 0000000000000000 R09: ffffffff860a0097
R10: ffff888116927b98 R11: 0000000000000001 R12: 0000000000000000
R13: ffff88811959b0f8 R14: 00000000fffffff0 R15: 0000000000000000
FS:  00007f00232a3700(0000) GS:ffff88811ae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff79859fb0 CR3: 000000010a18a005 CR4: 0000000000770ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
  <TASK>
  ? die_addr+0x38/0xa0
  ? exc_general_protection+0x144/0x220
  ? asm_exc_general_protection+0x22/0x30
  ? __device_attach+0xa9/0x450
  ? __device_attach+0x76/0x450
  ? __pfx___device_attach+0x10/0x10
  ? usb_ifnum_to_if+0x140/0x1d0
  proc_ioctl.part.0+0x3ff/0x4a0
  usbdev_ioctl+0x178a/0x3f70
  ? __pfx_usbdev_ioctl+0x10/0x10
  ? __pfx___lock_acquire+0x10/0x10
  ? do_vfs_ioctl+0x120/0x1480
  ? __pfx_do_vfs_ioctl+0x10/0x10
  ? find_held_lock+0x2c/0x110
  ? __fget_files+0x1f8/0x420
  ? lock_release+0x3c3/0x6a0
  ? __pfx_lock_release+0x10/0x10
  ? lock_release+0x3c3/0x6a0
  ? __fget_files+0x21a/0x420
  ? __pfx_usbdev_ioctl+0x10/0x10
  __x64_sys_ioctl+0x171/0x1e0
  do_syscall_64+0x38/0x90
  entry_SYSCALL_64_after_hwframe+0x72/0xdc
RIP: 0033:0x4699cd
Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 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:00007f00232a2c58 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000057c008 RCX: 00000000004699cd
RDX: 0000000020000180 RSI: 00000000c0105512 RDI: 0000000000000003
RBP: 00000000004d4a17 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000057c008
R13: 00007ffe93c75b1f R14: 00007ffe93c75cc0 R15: 00007f00232a2dc0
  </TASK>



---
drivers/base/dd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 9c09ca5c4..fcd83226a 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -1003,7 +1003,7 @@ static int __device_attach(struct device *dev, bool allow_async)
        bool async = false;

        device_lock(dev);
-       if (dev->p->dead) {
+       if (!dev->p||dev->p->dead) {
                goto out_unlock;
        } else if (dev->driver) {
                if (device_is_bound(dev)) { 

base-commit: 6995e2de6891c724bfeb2db33d7b87775f913ad1 (grafted, HEAD, tag: v6.4)