[syzbot] [dri?] WARNING in drm_property_add_enum

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f5bbbfec59b4 Merge tag 'probes-fixes-v7.2-rc7' of git://gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=132db479580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8a233ed2ce9a8096
dashboard link: https://syzkaller.appspot.com/bug?extid=916c888ba5f1a54c9526
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
userspace arch: i386
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=105c4c79580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15a91149580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-f5bbbfec.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/48f3b996e46b/vmlinux-f5bbbfec.xz
kernel image: https://storage.googleapis.com/syzbot-assets/523783d7181e/bzImage-f5bbbfec.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+916c88...@syzkaller.appspotmail.com

usb 5-1: config 1 interface 0 altsetting 0 has 1 endpoint descriptor, different from the interface descriptor's value: 2
usb 5-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
------------[ cut here ]------------
strlen(name) >= DRM_PROP_NAME_LEN
WARNING: drivers/gpu/drm/drm_property.c:396 at drm_property_add_enum+0x4ac/0x590 drivers/gpu/drm/drm_property.c:396, CPU#2: kworker/2:3/5894
Modules linked in:
CPU: 2 UID: 0 PID: 5894 Comm: kworker/2:3 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
Workqueue: usb_hub_wq hub_event
RIP: 0010:drm_property_add_enum+0x4ac/0x590 drivers/gpu/drm/drm_property.c:396
Code: 03 80 3c 02 00 0f 85 89 00 00 00 49 89 2c 24 31 db e9 fc fc ff ff e8 f3 e9 43 fc 90 0f 0b 90 e9 e9 fc ff ff e8 e5 e9 43 fc 90 <0f> 0b 90 e9 db fc ff ff e8 87 7e b3 fc e9 b3 fb ff ff e8 cd e9 43
RSP: 0000:ffffc90002fd6cf0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000050 RCX: ffffffff85c5e14d
RDX: ffff888027ba0000 RSI: ffffffff85c5e5bb RDI: ffff888027ba0000
RBP: 0000000000000000 R08: 0000000000000007 R09: 000000000000001f
R10: 0000000000000050 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000005 R14: ffff88802a8e4100 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff888096df3000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055d682c98168 CR3: 000000004ce67000 CR4: 0000000000352ef0
Call Trace:
<TASK>
drm_mode_create_tv_properties_legacy+0x3e9/0x4c0 drivers/gpu/drm/drm_connector.c:2216
gud_connector_add_tv_mode+0x1d7/0x2b0 drivers/gpu/drm/gud/gud_connector.c:402
gud_connector_add_properties drivers/gpu/drm/gud/gud_connector.c:525 [inline]
gud_connector_create drivers/gpu/drm/gud/gud_connector.c:680 [inline]
gud_get_connectors+0xbd9/0x1700 drivers/gpu/drm/gud/gud_connector.c:717
gud_probe+0x17aa/0x1c20 drivers/gpu/drm/gud/gud_drv.c:635
usb_probe_interface+0x303/0x8f0 drivers/usb/core/driver.c:396
call_driver_probe drivers/base/dd.c:628 [inline]
really_probe+0x241/0xa60 drivers/base/dd.c:706
__driver_probe_device+0x20e/0x450 drivers/base/dd.c:868
driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
__device_attach_driver+0x1df/0x320 drivers/base/dd.c:1026
bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:500
__device_attach+0x1e4/0x4d0 drivers/base/dd.c:1098
device_initial_probe+0xaf/0xd0 drivers/base/dd.c:1153
bus_probe_device+0x64/0x160 drivers/base/bus.c:620
device_add+0x121d/0x1970 drivers/base/core.c:3772
usb_set_configuration+0xd97/0x1c60 drivers/usb/core/message.c:2268
usb_generic_driver_probe+0xa1/0xe0 drivers/usb/core/generic.c:250
usb_probe_device+0xef/0x400 drivers/usb/core/driver.c:291
call_driver_probe drivers/base/dd.c:628 [inline]
really_probe+0x241/0xa60 drivers/base/dd.c:706
__driver_probe_device+0x20e/0x450 drivers/base/dd.c:868
driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
__device_attach_driver+0x1df/0x320 drivers/base/dd.c:1026
bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:500
__device_attach+0x1e4/0x4d0 drivers/base/dd.c:1098
device_initial_probe+0xaf/0xd0 drivers/base/dd.c:1153
bus_probe_device+0x64/0x160 drivers/base/bus.c:620
device_add+0x121d/0x1970 drivers/base/core.c:3772
usb_new_device.part.0+0xcc2/0x1686 drivers/usb/core/hub.c:2703
usb_new_device include/linux/workqueue.h:714 [inline]
hub_port_connect drivers/usb/core/hub.c:5575 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5715 [inline]
port_event drivers/usb/core/hub.c:5879 [inline]
hub_event.cold+0x1e3/0xe90 drivers/usb/core/hub.c:5961
process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
process_scheduled_works kernel/workqueue.c:3405 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486
kthread+0x370/0x450 kernel/kthread.c:436
ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>


---
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[syzbot]

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***

Subject: [PATCH] drm/gud: NUL-terminate TV mode names read from the device
Author: karti...@gmail.com

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


gud_connector_add_tv_mode() reads a buffer of fixed-size mode names from
the USB device and passes pointers into it to
drm_mode_create_tv_properties_legacy(), which calls strlen() on each one.
Nothing guarantees the device NUL-terminates a name, so strlen() can run
past the end of a slot and, for the last mode, past the end of the
allocation.

Terminate each name at the end of its slot before use.

Reported-by: syzbot+916c88...@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=916c888ba5f1a54c9526
Signed-off-by: Deepanshu Kartikey <karti...@gmail.com>
---
drivers/gpu/drm/gud/gud_connector.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/gud/gud_connector.c b/drivers/gpu/drm/gud/gud_connector.c
index ea0cca58b7c8..5c0065c876a7 100644
--- a/drivers/gpu/drm/gud/gud_connector.c
+++ b/drivers/gpu/drm/gud/gud_connector.c
@@ -396,8 +396,13 @@ static int gud_connector_add_tv_mode(struct gud_device *gdrm, struct drm_connect
}

num_modes = ret / GUD_CONNECTOR_TV_MODE_NAME_LEN;
- for (i = 0; i < num_modes; i++)
- modes[i] = &buf[i * GUD_CONNECTOR_TV_MODE_NAME_LEN];
+ for (i = 0; i < num_modes; i++) {
+ char *mode = &buf[i * GUD_CONNECTOR_TV_MODE_NAME_LEN];
+
+ /* The device is not trusted to NUL-terminate the name */
+ mode[GUD_CONNECTOR_TV_MODE_NAME_LEN - 1] = '\0';
+ modes[i] = mode;
+ }

ret = drm_mode_create_tv_properties_legacy(connector->dev, num_modes, modes);
free:
--
2.43.0

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+916c88...@syzkaller.appspotmail.com
Tested-by: syzbot+916c88...@syzkaller.appspotmail.com

Tested on:

commit: 3eb40771 Merge tag 'soc-fixes-7.2-3' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12261949580000

kernel config: https://syzkaller.appspot.com/x/.config?x=8a233ed2ce9a8096
dashboard link: https://syzkaller.appspot.com/bug?extid=916c888ba5f1a54c9526
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
userspace arch: i386

patch: https://syzkaller.appspot.com/x/patch.diff?x=1047c6c6580000

Note: testing is done by a robot and is best-effort only.