arch_topology: Fix incorrect error check in topology_parse_cpu_capacity()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: arch_topology: Fix incorrect error check in topology_parse_cpu_capacity() Fix incorrect use of PTR_ERR_OR_ZERO() in topology_parse_cpu_capacity() which causes the code to proceed with NULL clock pointers. The current logic uses !PTR_ERR_OR_ZERO(cpu_clk) which evaluates to true for both valid pointers and NULL, leading to potential NULL pointer dereference in clk_get_rate(). Per include/linux/err.h documentation, PTR_ERR_OR_ZERO(ptr) returns: "The error code within @ptr if it is an error pointer; 0 otherwise." This means PTR_ERR_OR_ZERO() returns 0 for both valid pointers AND NULL pointers. Therefore !PTR_ERR_OR_ZERO(cpu_clk) evaluates to true (proceed) when cpu_clk is either valid or NULL, causing clk_get_rate(NULL) to be called when of_clk_get() returns NULL. Replace with !IS_ERR_OR_NULL(cpu_clk) which only proceeds for valid pointers, preventing potential NULL pointer dereference in clk_get_rate().

References

• https://git.kernel.org/stable/c/64da320252e43456cc9ec3055ff567f168467b37
• https://git.kernel.org/stable/c/02fbea0864fd4a863671f5d418129258d7159f68
• https://git.kernel.org/stable/c/a77f8434954cb1e9c42c3854e40855fdcf5ab235
• https://git.kernel.org/stable/c/3373f263bb647fcc3b5237cfaef757633b9ee25e
• https://git.kernel.org/stable/c/45379303124487db3a81219af7565d41f498167f
• https://git.kernel.org/stable/c/3a01b2614e84361aa222f67bc628593987e5cdb2
• https://git.kernel.org/stable/c/2eead19334516c8e9927c11b448fbe512b1f18a1