kernel/linux.git/init/main.c, branch v4.14.286

random: handle latent entropy and command line from random_init()

2022-06-25T09:46:40+00:00

commit 2f14062bb14b0fcfcc21e6dc7d5b5c0d25966164 upstream. Currently, start_kernel() adds latent entropy and the command line to the entropy bool *after* the RNG has been initialized, deferring when it's actually used by things like stack canaries until the next time the pool is seeded. This surely is not intended. Rather than splitting up which entropy gets added where and when between start_kernel() and random_init(), just do everything in random_init(), which should eliminate these kinds of bugs in the future. While we're at it, rename the awkwardly titled "rand_initialize()" to the more standard "random_init()" nomenclature. Reviewed-by: Dominik Brodowski Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman

init: call time_init() before rand_initialize()

2022-06-25T09:46:38+00:00

commit fe222a6ca2d53c38433cba5d3be62a39099e708e upstream. Currently time_init() is called after rand_initialize(), but rand_initialize() makes use of the timer on various platforms, and sometimes this timer needs to be initialized by time_init() first. In order for random_get_entropy() to not return zero during early boot when it's potentially used as an entropy source, reverse the order of these two calls. The block doing random initialization was right before time_init() before, so changing the order shouldn't have any complicated effects. Cc: Andrew Morton Reviewed-by: Stafford Horne Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman

random: move rand_initialize() earlier

2022-06-25T09:46:26+00:00

commit d55535232c3dbde9a523a9d10d68670f5fe5dec3 upstream. Right now rand_initialize() is run as an early_initcall(), but it only depends on timekeeping_init() (for mixing ktime_get_real() into the pools). However, the call to boot_init_stack_canary() for stack canary initialization runs earlier, which triggers a warning at boot: random: get_random_bytes called from start_kernel+0x357/0x548 with crng_init=0 Instead, this moves rand_initialize() to after timekeeping_init(), and moves canary initialization here as well. Note that this warning may still remain for machines that do not have UEFI RNG support (which initializes the RNG pools during setup_arch()), or for x86 machines without RDRAND (or booting without "random.trust=on" or CONFIG_RANDOM_TRUST_CPU=y). Signed-off-by: Kees Cook Signed-off-by: Theodore Ts'o Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman

init/main.c: return 1 from handled __setup() functions

2022-04-20T07:08:28+00:00

[ Upstream commit f9a40b0890658330c83c95511f9d6b396610defc ] initcall_blacklist() should return 1 to indicate that it handled its cmdline arguments. set_debug_rodata() should return 1 to indicate that it handled its cmdline arguments. Print a warning if the option string is invalid. This prevents these strings from being added to the 'init' program's environment as they are not init arguments/parameters. Link: https://lkml.kernel.org/r/20220221050901.23985-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap Reported-by: Igor Zhbanov Cc: Ingo Molnar Cc: Greg Kroah-Hartman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

pid: take a reference when initializing `cad_pid`

2021-06-10T10:43:51+00:00

commit 0711f0d7050b9e07c44bc159bbc64ac0a1022c7f upstream. During boot, kernel_init_freeable() initializes `cad_pid` to the init task's struct pid. Later on, we may change `cad_pid` via a sysctl, and when this happens proc_do_cad_pid() will increment the refcount on the new pid via get_pid(), and will decrement the refcount on the old pid via put_pid(). As we never called get_pid() when we initialized `cad_pid`, we decrement a reference we never incremented, can therefore free the init task's struct pid early. As there can be dangling references to the struct pid, we can later encounter a use-after-free (e.g. when delivering signals). This was spotted when fuzzing v5.13-rc3 with Syzkaller, but seems to have been around since the conversion of `cad_pid` to struct pid in commit 9ec52099e4b8 ("[PATCH] replace cad_pid by a struct pid") from the pre-KASAN stone age of v2.6.19. Fix this by getting a reference to the init task's struct pid when we assign it to `cad_pid`. Full KASAN splat below. ================================================================== BUG: KASAN: use-after-free in ns_of_pid include/linux/pid.h:153 [inline] BUG: KASAN: use-after-free in task_active_pid_ns+0xc0/0xc8 kernel/pid.c:509 Read of size 4 at addr ffff23794dda0004 by task syz-executor.0/273 CPU: 1 PID: 273 Comm: syz-executor.0 Not tainted 5.12.0-00001-g9aef892b2d15 #1 Hardware name: linux,dummy-virt (DT) Call trace: ns_of_pid include/linux/pid.h:153 [inline] task_active_pid_ns+0xc0/0xc8 kernel/pid.c:509 do_notify_parent+0x308/0xe60 kernel/signal.c:1950 exit_notify kernel/exit.c:682 [inline] do_exit+0x2334/0x2bd0 kernel/exit.c:845 do_group_exit+0x108/0x2c8 kernel/exit.c:922 get_signal+0x4e4/0x2a88 kernel/signal.c:2781 do_signal arch/arm64/kernel/signal.c:882 [inline] do_notify_resume+0x300/0x970 arch/arm64/kernel/signal.c:936 work_pending+0xc/0x2dc Allocated by task 0: slab_post_alloc_hook+0x50/0x5c0 mm/slab.h:516 slab_alloc_node mm/slub.c:2907 [inline] slab_alloc mm/slub.c:2915 [inline] kmem_cache_alloc+0x1f4/0x4c0 mm/slub.c:2920 alloc_pid+0xdc/0xc00 kernel/pid.c:180 copy_process+0x2794/0x5e18 kernel/fork.c:2129 kernel_clone+0x194/0x13c8 kernel/fork.c:2500 kernel_thread+0xd4/0x110 kernel/fork.c:2552 rest_init+0x44/0x4a0 init/main.c:687 arch_call_rest_init+0x1c/0x28 start_kernel+0x520/0x554 init/main.c:1064 0x0 Freed by task 270: slab_free_hook mm/slub.c:1562 [inline] slab_free_freelist_hook+0x98/0x260 mm/slub.c:1600 slab_free mm/slub.c:3161 [inline] kmem_cache_free+0x224/0x8e0 mm/slub.c:3177 put_pid.part.4+0xe0/0x1a8 kernel/pid.c:114 put_pid+0x30/0x48 kernel/pid.c:109 proc_do_cad_pid+0x190/0x1b0 kernel/sysctl.c:1401 proc_sys_call_handler+0x338/0x4b0 fs/proc/proc_sysctl.c:591 proc_sys_write+0x34/0x48 fs/proc/proc_sysctl.c:617 call_write_iter include/linux/fs.h:1977 [inline] new_sync_write+0x3ac/0x510 fs/read_write.c:518 vfs_write fs/read_write.c:605 [inline] vfs_write+0x9c4/0x1018 fs/read_write.c:585 ksys_write+0x124/0x240 fs/read_write.c:658 __do_sys_write fs/read_write.c:670 [inline] __se_sys_write fs/read_write.c:667 [inline] __arm64_sys_write+0x78/0xb0 fs/read_write.c:667 __invoke_syscall arch/arm64/kernel/syscall.c:37 [inline] invoke_syscall arch/arm64/kernel/syscall.c:49 [inline] el0_svc_common.constprop.1+0x16c/0x388 arch/arm64/kernel/syscall.c:129 do_el0_svc+0xf8/0x150 arch/arm64/kernel/syscall.c:168 el0_svc+0x28/0x38 arch/arm64/kernel/entry-common.c:416 el0_sync_handler+0x134/0x180 arch/arm64/kernel/entry-common.c:432 el0_sync+0x154/0x180 arch/arm64/kernel/entry.S:701 The buggy address belongs to the object at ffff23794dda0000 which belongs to the cache pid of size 224 The buggy address is located 4 bytes inside of 224-byte region [ffff23794dda0000, ffff23794dda00e0) The buggy address belongs to the page: page:(____ptrval____) refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4dda0 head:(____ptrval____) order:1 compound_mapcount:0 flags: 0x3fffc0000010200(slab|head) raw: 03fffc0000010200 dead000000000100 dead000000000122 ffff23794d40d080 raw: 0000000000000000 0000000000190019 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff23794dd9ff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff23794dd9ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff23794dda0000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff23794dda0080: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff23794dda0100: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00 ================================================================== Link: https://lkml.kernel.org/r/20210524172230.38715-1-mark.rutland@arm.com Fixes: 9ec52099e4b8678a ("[PATCH] replace cad_pid by a struct pid") Signed-off-by: Mark Rutland Acked-by: Christian Brauner Cc: Cedric Le Goater Cc: Christian Brauner Cc: Eric W. Biederman Cc: Kees Cook Cc: Paul Mackerras Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

x86: Fix early boot crash on gcc-10, third try

2020-05-20T06:17:15+00:00

commit a9a3ed1eff3601b63aea4fb462d8b3b92c7c1e7e upstream. ... or the odyssey of trying to disable the stack protector for the function which generates the stack canary value. The whole story started with Sergei reporting a boot crash with a kernel built with gcc-10: Kernel panic — not syncing: stack-protector: Kernel stack is corrupted in: start_secondary CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.6.0-rc5—00235—gfffb08b37df9 #139 Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./H77M—D3H, BIOS F12 11/14/2013 Call Trace: dump_stack panic ? start_secondary __stack_chk_fail start_secondary secondary_startup_64 -—-[ end Kernel panic — not syncing: stack—protector: Kernel stack is corrupted in: start_secondary This happens because gcc-10 tail-call optimizes the last function call in start_secondary() - cpu_startup_entry() - and thus emits a stack canary check which fails because the canary value changes after the boot_init_stack_canary() call. To fix that, the initial attempt was to mark the one function which generates the stack canary with: __attribute__((optimize("-fno-stack-protector"))) ... start_secondary(void *unused) however, using the optimize attribute doesn't work cumulatively as the attribute does not add to but rather replaces previously supplied optimization options - roughly all -fxxx options. The key one among them being -fno-omit-frame-pointer and thus leading to not present frame pointer - frame pointer which the kernel needs. The next attempt to prevent compilers from tail-call optimizing the last function call cpu_startup_entry(), shy of carving out start_secondary() into a separate compilation unit and building it with -fno-stack-protector, was to add an empty asm(""). This current solution was short and sweet, and reportedly, is supported by both compilers but we didn't get very far this time: future (LTO?) optimization passes could potentially eliminate this, which leads us to the third attempt: having an actual memory barrier there which the compiler cannot ignore or move around etc. That should hold for a long time, but hey we said that about the other two solutions too so... Reported-by: Sergei Trofimovich Signed-off-by: Borislav Petkov Tested-by: Kalle Valo Cc: Link: https://lkml.kernel.org/r/20200314164451.346497-1-slyfox@gentoo.org Signed-off-by: Greg Kroah-Hartman

fork: fix some -Wmissing-prototypes warnings

2019-12-05T14:37:52+00:00

[ Upstream commit fb5bf31722d0805a3f394f7d59f2e8cd07acccb7 ] We get a warning when building kernel with W=1: kernel/fork.c:167:13: warning: no previous prototype for `arch_release_thread_stack' [-Wmissing-prototypes] kernel/fork.c:779:13: warning: no previous prototype for `fork_init' [-Wmissing-prototypes] Add the missing declaration in head file to fix this. Also, remove arch_release_thread_stack() completely because no arch seems to implement it since bb9d81264 (arch: remove tile port). Link: http://lkml.kernel.org/r/1542170087-23645-1-git-send-email-wang.yi59@zte.com.cn Signed-off-by: Yi Wang Acked-by: Michal Hocko Acked-by: Mike Rapoport Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

init: initialize jump labels before command line option parsing

2019-05-16T17:42:23+00:00

[ Upstream commit 6041186a32585fc7a1d0f6cfe2f138b05fdc3c82 ] When a module option, or core kernel argument, toggles a static-key it requires jump labels to be initialized early. While x86, PowerPC, and ARM64 arrange for jump_label_init() to be called before parse_args(), ARM does not. Kernel command line: rdinit=/sbin/init page_alloc.shuffle=1 panic=-1 console=ttyAMA0,115200 page_alloc.shuffle=1 ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at ./include/linux/jump_label.h:303 page_alloc_shuffle+0x12c/0x1ac static_key_enable(): static key 'page_alloc_shuffle_key+0x0/0x4' used before call to jump_label_init() Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 5.1.0-rc4-next-20190410-00003-g3367c36ce744 #1 Hardware name: ARM Integrator/CP (Device Tree) [] (unwind_backtrace) from [] (show_stack+0x10/0x18) [] (show_stack) from [] (dump_stack+0x18/0x24) [] (dump_stack) from [] (__warn+0xe0/0x108) [] (__warn) from [] (warn_slowpath_fmt+0x44/0x6c) [] (warn_slowpath_fmt) from [] (page_alloc_shuffle+0x12c/0x1ac) [] (page_alloc_shuffle) from [] (shuffle_store+0x28/0x48) [] (shuffle_store) from [] (parse_args+0x1f4/0x350) [] (parse_args) from [] (start_kernel+0x1c0/0x488) Move the fallback call to jump_label_init() to occur before parse_args(). The redundant calls to jump_label_init() in other archs are left intact in case they have static key toggling use cases that are even earlier than option parsing. Link: http://lkml.kernel.org/r/155544804466.1032396.13418949511615676665.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams Reported-by: Guenter Roeck Reviewed-by: Kees Cook Cc: Mathieu Desnoyers Cc: Thomas Gleixner Cc: Mike Rapoport Cc: Russell King Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

Revert "mm: use early_pfn_to_nid in page_ext_init"

2019-03-23T13:35:13+00:00

[ Upstream commit 2f1ee0913ce58efe7f18fbd518bd54c598559b89 ] This reverts commit fe53ca54270a ("mm: use early_pfn_to_nid in page_ext_init"). When booting a system with "page_owner=on", start_kernel page_ext_init invoke_init_callbacks init_section_page_ext init_page_owner init_early_allocated_pages init_zones_in_node init_pages_in_zone lookup_page_ext page_to_nid The issue here is that page_to_nid() will not work since some page flags have no node information until later in page_alloc_init_late() due to DEFERRED_STRUCT_PAGE_INIT. Hence, it could trigger an out-of-bounds access with an invalid nid. UBSAN: Undefined behaviour in ./include/linux/mm.h:1104:50 index 7 is out of range for type 'zone [5]' Also, kernel will panic since flags were poisoned earlier with, CONFIG_DEBUG_VM_PGFLAGS=y CONFIG_NODE_NOT_IN_PAGE_FLAGS=n start_kernel setup_arch pagetable_init paging_init sparse_init sparse_init_nid memblock_alloc_try_nid_raw It did not handle it well in init_pages_in_zone() which ends up calling page_to_nid(). page:ffffea0004200000 is uninitialized and poisoned raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) page_owner info is not active (free page?) kernel BUG at include/linux/mm.h:990! RIP: 0010:init_page_owner+0x486/0x520 This means that assumptions behind commit fe53ca54270a ("mm: use early_pfn_to_nid in page_ext_init") are incomplete. Therefore, revert the commit for now. A proper way to move the page_owner initialization to sooner is to hook into memmap initialization. Link: http://lkml.kernel.org/r/20190115202812.75820-1-cai@lca.pw Signed-off-by: Qian Cai Acked-by: Michal Hocko Cc: Pasha Tatashin Cc: Mel Gorman Cc: Yang Shi Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

init: rename and re-order boot_cpu_state_init()

2018-08-15T16:12:48+00:00

commit b5b1404d0815894de0690de8a1ab58269e56eae6 upstream. This is purely a preparatory patch for upcoming changes during the 4.19 merge window. We have a function called "boot_cpu_state_init()" that isn't really about the bootup cpu state: that is done much earlier by the similarly named "boot_cpu_init()" (note lack of "state" in name). This function initializes some hotplug CPU state, and needs to run after the percpu data has been properly initialized. It even has a comment to that effect. Except it _doesn't_ actually run after the percpu data has been properly initialized. On x86 it happens to do that, but on at least arm and arm64, the percpu base pointers are initialized by the arch-specific 'smp_prepare_boot_cpu()' hook, which ran _after_ boot_cpu_state_init(). This had some unexpected results, and in particular we have a patch pending for the merge window that did the obvious cleanup of using 'this_cpu_write()' in the cpu hotplug init code: - per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE; + this_cpu_write(cpuhp_state.state, CPUHP_ONLINE); which is obviously the right thing to do. Except because of the ordering issue, it actually failed miserably and unexpectedly on arm64. So this just fixes the ordering, and changes the name of the function to be 'boot_cpu_hotplug_init()' to make it obvious that it's about cpu hotplug state, because the core CPU state was supposed to have already been done earlier. Marked for stable, since the (not yet merged) patch that will show this problem is marked for stable. Reported-by: Vlastimil Babka Reported-by: Mian Yousaf Kaukab Suggested-by: Catalin Marinas Acked-by: Thomas Gleixner Cc: Will Deacon Cc: stable@kernel.org Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman