HID: core: remove unnecessary WARN_ON() in implement()

Syzkaller hit a warning [1] in a call to implement() when trying
to write a value into a field of smaller size in an output report.

Since implement() already has a warn message printed out with the
help of hid_warn() and value in question gets trimmed with:
	...
	value &= m;
	...
WARN_ON may be considered superfluous. Remove it to suppress future
syzkaller triggers.

[1]
WARNING: CPU: 0 PID: 5084 at drivers/hid/hid-core.c:1451 implement drivers/hid/hid-core.c:1451 [inline]
WARNING: CPU: 0 PID: 5084 at drivers/hid/hid-core.c:1451 hid_output_report+0x548/0x760 drivers/hid/hid-core.c:1863
Modules linked in:
CPU: 0 PID: 5084 Comm: syz-executor424 Not tainted 6.9.0-rc7-syzkaller-00183-gcf87f46fd34d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
RIP: 0010:implement drivers/hid/hid-core.c:1451 [inline]
RIP: 0010:hid_output_report+0x548/0x760 drivers/hid/hid-core.c:1863
...
Call Trace:
 <TASK>
 __usbhid_submit_report drivers/hid/usbhid/hid-core.c:591 [inline]
 usbhid_submit_report+0x43d/0x9e0 drivers/hid/usbhid/hid-core.c:636
 hiddev_ioctl+0x138b/0x1f00 drivers/hid/usbhid/hiddev.c:726
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:904 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:890
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
...

Fixes: 95d1c8951e5b ("HID: simplify implement() a bit")
Reported-by: <syzbot+5186630949e3c55f0799@syzkaller.appspotmail.com>
Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index b1fa0378e8f4a422b4959cf2ec2589b719beb674..74efda212c55f53cbb6e05adb9cb5c8bf7e67cc2 100644 (file)
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1448,7 +1448,6 @@ static void implement(const struct hid_device *hid, u8 *report,
                        hid_warn(hid,
                                 "%s() called with too large value %d (n: %d)! (%s)\n",
                                 __func__, value, n, current->comm);
-                       WARN_ON(1);
                        value &= m;
                }
        }