In the Linux kernel, the following vulnerability has been resolved: ARM: integrator: Fix early initialization Starting with commit bdb249fce9ad4 ("ARM: integrator: read counter using syscon/regmap"), intcp_init_early calls syscon_regmap_lookup_by_compatible which in turn calls of_syscon_register. This function allocates memory. Since the memory management code has not been initialized at that time, the call always fails. It either returns -ENOMEM or crashes as follows. Unable to handle kernel NULL pointer dereference at virtual address 0000000c when read [0000000c] *pgd=00000000 Internal error: Oops: 5 [#1] ARM Modules linked in: CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 6.15.0-rc5-00026-g5fcc9bf84ee5 #1 PREEMPT Hardware name: ARM Integrator/CP (Device Tree) PC is at __kmalloc_cache_noprof+0xec/0x39c LR is at __kmalloc_cache_noprof+0x34/0x39c ... Call trace: __kmalloc_cache_noprof from of_syscon_register+0x7c/0x310 of_syscon_register from device_node_get_regmap+0xa4/0xb0 device_node_get_regmap from intcp_init_early+0xc/0x40 intcp_init_early from start_kernel+0x60/0x688 start_kernel from 0x0 The crash is seen due to a dereferenced pointer which is not supposed to be NULL but is NULL if the memory management subsystem has not been initialized. The crash is not seen with all versions of gcc. Some versions such as gcc 9.x apparently do not dereference the pointer, presumably if tracing is disabled. The problem has been reproduced with gcc 10.x, 11.x, and 13.x. Either case, if the crash is not seen, the call to syscon_regmap_lookup_by_compatible returns -ENOMEM, and sched_clock_register is never called. Fix the problem by moving the early initialization code into the standard machine initialization code.
https://git.kernel.org/stable/c/e984dc22e2c24dc34d6728e338c82b1ce7862753
https://git.kernel.org/stable/c/90d77b30a666049ad24df463f52e5d529c44e8cd
https://git.kernel.org/stable/c/812103fb6da904bd03d62cf6a9826e537318ceed
https://git.kernel.org/stable/c/6624854554c4c2bdfed3559e5c11bb03b16e7bd1
https://git.kernel.org/stable/c/58a112b0973f6cd6bcb8c503d1ff88be411ed0f0
https://git.kernel.org/stable/c/508b1193d63b5e073a3fe103eeb785fcba2d368c
https://git.kernel.org/stable/c/33ad014abec90f37dade0e00560f28864187e21a
https://git.kernel.org/stable/c/22c738fb51f2d8b23ddff5cc0ccb2dd685bb39d3