powerpc64/ftrace: fix module loading without patchable function entries

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: powerpc64/ftrace: fix module loading without patchable function entries get_stubs_size assumes that there must always be at least one patchable function entry, which is not always the case (modules that export data but no code), otherwise it returns -ENOEXEC and thus the section header sh_size is set to that value. During module_memory_alloc() the size is passed to execmem_alloc() after being page-aligned and thus set to zero which will cause it to fail the allocation (and thus module loading) as __vmalloc_node_range() checks for zero-sized allocs and returns null: [ 115.466896] module_64: cast_common: doesn't contain __patchable_function_entries. [ 115.469189] ------------[ cut here ]------------ [ 115.469496] WARNING: CPU: 0 PID: 274 at mm/vmalloc.c:3778 __vmalloc_node_range_noprof+0x8b4/0x8f0 ... [ 115.478574] ---[ end trace 0000000000000000 ]--- [ 115.479545] execmem: unable to allocate memory Fix this by removing the check completely, since it is anyway not helpful to propagate this as an error upwards.

References

• https://git.kernel.org/stable/c/358b559afec7806b9d01c2405b490e782c347022
• https://git.kernel.org/stable/c/534f5a8ba27863141e29766467a3e1f61bcb47ac