In the Linux kernel, the following vulnerability has been resolved: clk: eswin: Zero-initialize stack-allocated clk_init_data eswin_clk_register_pll() and eswin_register_clkdiv() declare a struct clk_init_data on the stack and only ini…

Overview

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

clk: eswin: Zero-initialize stack-allocated clk_init_data

eswin_clk_register_pll() and eswin_register_clkdiv() declare a struct clk_init_data on the stack and only initialize some of its fields (parent_data respectively parent_hws). clk_core_populate_parent_map() checks parent_names first and parent_data second before falling back to parent_hws, so leftover stack garbage in the uninitialized fields hijacks parent resolution and the clk core dereferences a bogus pointer:

Unable to handle kernel NULL pointer dereference at virtual address 000000000000000c Oops [#1] epc : __clk_register+0x31a/0x7f0 [<ffffffff805dc774>] __clk_register+0x31a/0x7f0 [<ffffffff805dcd76>] devm_clk_hw_register+0x2a/0x94 [<ffffffff805e319a>] eswin_register_clkdiv+0x80/0xd0 [<ffffffff805e34a0>] eswin_clk_register_clks+0x162/0x1a0 [<ffffffff805e3736>] eic7700_clk_probe+0x146/0x180 [<ffffffff8065d23c>] platform_probe+0x3c/0x7a

Observed on EIC7700 hardware (with the driver backported to a 6.17 tree); whether the bug triggers depends entirely on what the stack happens to contain when the registration helpers run.

Zero-initialize both structures.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.