Re: KASAN: slab-out-of-bounds Read in hidraw_ioctl

[Andrey Konovalov <andreyknvl@google.com>]

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On Wed, Aug 21, 2019 at 2:57 PM Andrey Konovalov <andreyknvl@google.com> wrote:
>
> On Sun, Aug 11, 2019 at 10:46 PM syzbot
> <syzbot+5a6c4ec678a0c6ee84ba@syzkaller.appspotmail.com> wrote:
> >
> > syzbot has found a reproducer for the following crash on:
> >
> > HEAD commit:    e96407b4 usb-fuzzer: main usb gadget fuzzer driver
> > git tree:       https://github.com/google/kasan.git usb-fuzzer
> > console output: https://syzkaller.appspot.com/x/log.txt?x=150426ba600000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=cfa2c18fb6a8068e
> > dashboard link: https://syzkaller.appspot.com/bug?extid=5a6c4ec678a0c6ee84ba
> > compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12725c02600000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=162163c2600000
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+5a6c4ec678a0c6ee84ba@syzkaller.appspotmail.com
> >
> > ==================================================================
> > BUG: KASAN: slab-out-of-bounds in strlen+0x79/0x90 lib/string.c:525
> > Read of size 1 at addr ffff8881d29bdf38 by task syz-executor201/1726
> >
> > CPU: 1 PID: 1726 Comm: syz-executor201 Not tainted 5.3.0-rc2+ #25
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > Google 01/01/2011
> > Call Trace:
> >   __dump_stack lib/dump_stack.c:77 [inline]
> >   dump_stack+0xca/0x13e lib/dump_stack.c:113
> >   print_address_description+0x6a/0x32c mm/kasan/report.c:351
> >   __kasan_report.cold+0x1a/0x33 mm/kasan/report.c:482
> >   kasan_report+0xe/0x12 mm/kasan/common.c:612
> >   strlen+0x79/0x90 lib/string.c:525
> >   strlen include/linux/string.h:281 [inline]
> >   hidraw_ioctl+0x245/0xae0 drivers/hid/hidraw.c:446
> >   vfs_ioctl fs/ioctl.c:46 [inline]
> >   file_ioctl fs/ioctl.c:509 [inline]
> >   do_vfs_ioctl+0xd2d/0x1330 fs/ioctl.c:696
> >   ksys_ioctl+0x9b/0xc0 fs/ioctl.c:713
> >   __do_sys_ioctl fs/ioctl.c:720 [inline]
> >   __se_sys_ioctl fs/ioctl.c:718 [inline]
> >   __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:718
> >   do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296
> >   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> > RIP: 0033:0x445679
> > Code: e8 5c ad 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 0f 83 9b cd fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > RSP: 002b:00007ffc8514f3a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000445679
> > RDX: 0000000000000000 RSI: 0000000080404805 RDI: 0000000000000004
> > RBP: 00000000006d0018 R08: 000000000000000b R09: 00000000004002e0
> > R10: 000000000000000f R11: 0000000000000246 R12: 00000000004028a0
> > R13: 0000000000402930 R14: 0000000000000000 R15: 0000000000000000
> >
> > Allocated by task 0:
> > (stack is not available)
> >
> > Freed by task 0:
> > (stack is not available)
> >
> > The buggy address belongs to the object at ffff8881d29bde60
> >   which belongs to the cache shmem_inode_cache of size 1168
> > The buggy address is located 216 bytes inside of
> >   1168-byte region [ffff8881d29bde60, ffff8881d29be2f0)
> > The buggy address belongs to the page:
> > page:ffffea00074a6f00 refcount:1 mapcount:0 mapping:ffff8881da115180
> > index:0x0 compound_mapcount: 0
> > flags: 0x200000000010200(slab|head)
> > raw: 0200000000010200 dead000000000100 dead000000000122 ffff8881da115180
> > raw: 0000000000000000 00000000800c000c 00000001ffffffff 0000000000000000
> > page dumped because: kasan: bad access detected
> >
> > Memory state around the buggy address:
> >   ffff8881d29bde00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >   ffff8881d29bde80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> > > ffff8881d29bdf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >                                          ^
> >   ffff8881d29bdf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >   ffff8881d29be000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> > ==================================================================
> >
>
> Trying Alan's fix from another thread here:
>
> #syz test: https://github.com/google/kasan.git usb-fuzzer e96407b4

><

#syz test: https://github.com/google/kasan.git e96407b4

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Index: usb-devel/drivers/hid/hid-lg.c
===================================================================
--- usb-devel.orig/drivers/hid/hid-lg.c
+++ usb-devel/drivers/hid/hid-lg.c
@@ -818,7 +818,7 @@ static int lg_probe(struct hid_device *h
 
 		if (!buf) {
 			ret = -ENOMEM;
-			goto err_free;
+			goto err_stop;
 		}
 
 		ret = hid_hw_raw_request(hdev, buf[0], buf, sizeof(cbuf),
@@ -850,9 +850,12 @@ static int lg_probe(struct hid_device *h
 		ret = lg4ff_init(hdev);
 
 	if (ret)
-		goto err_free;
+		goto err_stop;
 
 	return 0;
+
+err_stop:
+	hid_hw_stop(hdev);
 err_free:
 	kfree(drv_data);
 	return ret;
@@ -863,8 +866,7 @@ static void lg_remove(struct hid_device
 	struct lg_drv_data *drv_data = hid_get_drvdata(hdev);
 	if (drv_data->quirks & LG_FF4)
 		lg4ff_deinit(hdev);
-	else
-		hid_hw_stop(hdev);
+	hid_hw_stop(hdev);
 	kfree(drv_data);
 }
 
Index: usb-devel/drivers/hid/hid-lg4ff.c
===================================================================
--- usb-devel.orig/drivers/hid/hid-lg4ff.c
+++ usb-devel/drivers/hid/hid-lg4ff.c
@@ -1477,7 +1477,6 @@ int lg4ff_deinit(struct hid_device *hid)
 		}
 	}
 #endif
-	hid_hw_stop(hid);
 	drv_data->device_props = NULL;
 
 	kfree(entry);