[syzbot] [usb?] general protection fault in adsl_state_store

[syzbot] [usb?] general protection fault in adsl_state_store

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    3eb40771c00a Merge tag 'soc-fixes-7.2-3' of git://git.kern..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12fc9949580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1d67342c314f228d
dashboard link: https://syzkaller.appspot.com/bug?extid=9b195c4f412ea5c4e56a
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17334679580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9b195c4f412ea5c4e56a@syzkaller.appspotmail.com

cxacru_cm: 3 callbacks suppressed
cxacru 5-1:1.0: send of cm 0x85 failed (-104)
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 0 UID: 0 PID: 6032 Comm: syz-executor219 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:adsl_state_store.cold+0x5d/0x15d drivers/usb/atm/cxacru.c:359
Code: 48 89 fa 48 c1 ea 03 80 3c 02 00 74 05 e8 a3 89 27 01 48 8b 6d 78 b8 ff ff 37 00 48 c1 e0 2a 48 8d 7d 10 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e d5 00 00 00 8b 75 10 89 da 48
RSP: 0018:ffffc900038e7bb0 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 00000000ffffff98 RCX: ffffffff87c43ce9
RDX: 0000000000000002 RSI: ffffffff8153789d RDI: 0000000000000010
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 00000000ffffff98 R11: ffffffff81d6107c R12: ffffc900038e7be8
R13: 0000000000000004 R14: ffff8880478ad800 R15: 1ffff9200071cf79
FS:  000055558821b400(0000) GS:ffff8880d5bde000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000560168e483b8 CR3: 00000000361a1000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 dev_attr_store+0x58/0x80 drivers/base/core.c:2505
 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x6ac/0x1050 fs/read_write.c:687
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff46eca73de
Code: 08 0f 85 f5 e2 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08
RSP: 002b:00007fffbb5e0ef8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000055558821b400 RCX: 00007ff46eca73de
RDX: 0000000000000004 RSI: 00007ff46ecf2074 RDI: 0000000000000005
RBP: 000055558821d890 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff46ecf4540
R13: 0000000000000000 R14: 0000000000000005 R15: 00007ff46ecf4590
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:adsl_state_store.cold+0x5d/0x15d drivers/usb/atm/cxacru.c:359
Code: 48 89 fa 48 c1 ea 03 80 3c 02 00 74 05 e8 a3 89 27 01 48 8b 6d 78 b8 ff ff 37 00 48 c1 e0 2a 48 8d 7d 10 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e d5 00 00 00 8b 75 10 89 da 48
RSP: 0018:ffffc900038e7bb0 EFLAGS: 00010202

RAX: dffffc0000000000 RBX: 00000000ffffff98 RCX: ffffffff87c43ce9
RDX: 0000000000000002 RSI: ffffffff8153789d RDI: 0000000000000010
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 00000000ffffff98 R11: ffffffff81d6107c R12: ffffc900038e7be8
R13: 0000000000000004 R14: ffff8880478ad800 R15: 1ffff9200071cf79
FS:  000055558821b400(0000) GS:ffff8880d5cde000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb3d476b0f5 CR3: 00000000361a1000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	48 89 fa             	mov    %rdi,%rdx
   3:	48 c1 ea 03          	shr    $0x3,%rdx
   7:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
   b:	74 05                	je     0x12
   d:	e8 a3 89 27 01       	call   0x12789b5
  12:	48 8b 6d 78          	mov    0x78(%rbp),%rbp
  16:	b8 ff ff 37 00       	mov    $0x37ffff,%eax
  1b:	48 c1 e0 2a          	shl    $0x2a,%rax
  1f:	48 8d 7d 10          	lea    0x10(%rbp),%rdi
  23:	48 89 fa             	mov    %rdi,%rdx
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	0f b6 04 02          	movzbl (%rdx,%rax,1),%eax <-- trapping instruction
  2e:	84 c0                	test   %al,%al
  30:	74 08                	je     0x3a
  32:	3c 03                	cmp    $0x3,%al
  34:	0f 8e d5 00 00 00    	jle    0x10f
  3a:	8b 75 10             	mov    0x10(%rbp),%esi
  3d:	89 da                	mov    %ebx,%edx
  3f:	48                   	rex.W


---
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Forwarded: Re: [syzbot] [usb?] general protection fault in adsl_state_store

[syzbot]

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***

Subject: Re: [syzbot] [usb?] general protection fault in adsl_state_store
Author: jie.wang@intel.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

diff --git a/drivers/usb/atm/cxacru.c b/drivers/usb/atm/cxacru.c
index 75d87c31e81f4..4322553f2902c 100644
--- a/drivers/usb/atm/cxacru.c
+++ b/drivers/usb/atm/cxacru.c
@@ -356,7 +356,7 @@ static ssize_t adsl_state_store(struct device *dev,
 	if (!strcmp(str_cmd, "stop") || !strcmp(str_cmd, "restart")) {
 		ret = cxacru_cm(instance, CM_REQUEST_CHIP_ADSL_LINE_STOP, NULL, 0, NULL, 0);
 		if (ret < 0) {
-			atm_err(instance->usbatm, "change adsl state:"
+			usb_err(instance->usbatm, "change adsl state:"
 				" CHIP_ADSL_LINE_STOP returned %d\n", ret);
 
 			ret = -EIO;
@@ -376,7 +376,7 @@ static ssize_t adsl_state_store(struct device *dev,
 	if (!strcmp(str_cmd, "start") || !strcmp(str_cmd, "restart")) {
 		ret = cxacru_cm(instance, CM_REQUEST_CHIP_ADSL_LINE_START, NULL, 0, NULL, 0);
 		if (ret < 0) {
-			atm_err(instance->usbatm, "change adsl state:"
+			usb_err(instance->usbatm, "change adsl state:"
 				" CHIP_ADSL_LINE_START returned %d\n", ret);
 
 			ret = -EIO;
@@ -481,7 +481,7 @@ static ssize_t adsl_config_store(struct device *dev,
 			ret = cxacru_cm(instance, CM_REQUEST_CARD_DATA_SET,
 				(u8 *) data, 4 + num * 8, NULL, 0);
 			if (ret < 0) {
-				atm_err(instance->usbatm,
+				usb_err(instance->usbatm,
 					"set card data returned %d\n", ret);
 				return -EIO;
 			}
@@ -490,7 +490,7 @@ static ssize_t adsl_config_store(struct device *dev,
 				snprintf(log + tmp*12, 13, " %02x=%08x",
 					le32_to_cpu(data[tmp * 2 + 1]),
 					le32_to_cpu(data[tmp * 2 + 2]));
-			atm_info(instance->usbatm, "config%s\n", log);
+			usb_info(instance->usbatm, "config%s\n", log);
 			num = 0;
 		}
 	}
@@ -827,6 +827,12 @@ static void cxacru_poll_status(struct work_struct *work)
 	int keep_polling = 1;
 	int ret;
 
+	/* adsl_state_store() calls this directly, before the heavy-init thread
+	 * has set up atm_dev; bail out rather than dereference NULL below.
+	 */
+	if (!atm_dev)
+		return;
+
 	ret = cxacru_cm_get_array(instance, CM_REQUEST_CARD_INFO_GET, buf, CXINF_MAX);
 	if (ret < 0) {
 		if (ret != -ESHUTDOWN)