CVE-2024-39509: Reachable Assertion

In the Linux kernel, the following vulnerability has been resolved:

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 ...