CVE-2025-40245

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> nios2: ensure that memblock.current_limit is set when setting pfn limits<br /> <br /> On nios2, with CONFIG_FLATMEM set, the kernel relies on<br /> memblock_get_current_limit() to determine the limits of mem_map, in<br /> particular for max_low_pfn.<br /> Unfortunately, memblock.current_limit is only default initialized to<br /> MEMBLOCK_ALLOC_ANYWHERE at this point of the bootup, potentially leading<br /> to situations where max_low_pfn can erroneously exceed the value of<br /> max_pfn and, thus, the valid range of available DRAM.<br /> <br /> This can in turn cause kernel-level paging failures, e.g.:<br /> <br /> [ 76.900000] Unable to handle kernel paging request at virtual address 20303000<br /> [ 76.900000] ea = c0080890, ra = c000462c, cause = 14<br /> [ 76.900000] Kernel panic - not syncing: Oops<br /> [ 76.900000] ---[ end Kernel panic - not syncing: Oops ]---<br /> <br /> This patch fixes this by pre-calculating memblock.current_limit<br /> based on the upper limits of the available memory ranges via<br /> adjust_lowmem_bounds, a simplified version of the equivalent<br /> implementation within the arm architecture.