bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 43 insertions, 0 deletions

diff --git a/Documentation/input/devices/cs461x.rst b/Documentation/input/devices/cs461x.rst
new file mode 100644
index 000000000..b1e6d508a
--- /dev/null
+++ b/Documentation/input/devices/cs461x.rst
@@ -0,0 +1,43 @@
+Crystal SoundFusion CS4610/CS4612/CS461 joystick
+================================================
+
+This is a new low-level driver to support analog joystick attached to
+Crystal SoundFusion CS4610/CS4612/CS4615. This code is based upon
+Vortex/Solo drivers as an example of decoration style, and ALSA
+0.5.8a kernel drivers as an chipset documentation and samples.
+
+This version does not have cooked mode support; the basic code
+is present here, but have not tested completely. The button analysis
+is completed in this mode, but the axis movement is not.
+
+Raw mode works fine with analog joystick front-end driver and cs461x
+driver as a backend. I've tested this driver with CS4610, 4-axis and
+4-button joystick; I mean the jstest utility. Also I've tried to
+play in xracer game using joystick, and the result is better than
+keyboard only mode.
+
+The sensitivity and calibrate quality have not been tested; the two
+reasons are performed: the same hardware cannot work under Win95 (blue
+screen in VJOYD); I have no documentation on my chip; and the existing
+behavior in my case was not raised the requirement of joystick calibration.
+So the driver have no code to perform hardware related calibration.
+
+This driver have the basic support for PCI devices only; there is no
+ISA or PnP ISA cards supported.
+
+The driver works with ALSA drivers simultaneously. For example, the xracer
+uses joystick as input device and PCM device as sound output in one time.
+There are no sound or input collisions detected. The source code have
+comments about them; but I've found the joystick can be initialized
+separately of ALSA modules. So, you can use only one joystick driver
+without ALSA drivers. The ALSA drivers are not needed to compile or
+run this driver.
+
+There are no debug information print have been placed in source, and no
+specific options required to work this driver. The found chipset parameters
+are printed via printk(KERN_INFO "..."), see the /var/log/messages to
+inspect cs461x: prefixed messages to determine possible card detection
+errors.
+
+Regards,
+Viktor