user/sven/linux.git/include/linux/sched, branch v5.4.276

kernel/fork: beware of __put_task_struct() calling context

2023-09-23T09:00:03Z

[ Upstream commit d243b34459cea30cfe5f3a9b2feb44e7daff9938 ] Under PREEMPT_RT, __put_task_struct() indirectly acquires sleeping locks. Therefore, it can't be called from an non-preemptible context. One practical example is splat inside inactive_task_timer(), which is called in a interrupt context: CPU: 1 PID: 2848 Comm: life Kdump: loaded Tainted: G W --------- Hardware name: HP ProLiant DL388p Gen8, BIOS P70 07/15/2012 Call Trace: dump_stack_lvl+0x57/0x7d mark_lock_irq.cold+0x33/0xba mark_lock+0x1e7/0x400 mark_usage+0x11d/0x140 __lock_acquire+0x30d/0x930 lock_acquire.part.0+0x9c/0x210 rt_spin_lock+0x27/0xe0 refill_obj_stock+0x3d/0x3a0 kmem_cache_free+0x357/0x560 inactive_task_timer+0x1ad/0x340 __run_hrtimer+0x8a/0x1a0 __hrtimer_run_queues+0x91/0x130 hrtimer_interrupt+0x10f/0x220 __sysvec_apic_timer_interrupt+0x7b/0xd0 sysvec_apic_timer_interrupt+0x4f/0xd0 asm_sysvec_apic_timer_interrupt+0x12/0x20 RIP: 0033:0x7fff196bf6f5 Instead of calling __put_task_struct() directly, we defer it using call_rcu(). A more natural approach would use a workqueue, but since in PREEMPT_RT, we can't allocate dynamic memory from atomic context, the code would become more complex because we would need to put the work_struct instance in the task_struct and initialize it when we allocate a new task_struct. The issue is reproducible with stress-ng: while true; do stress-ng --sched deadline --sched-period 1000000000 \ --sched-runtime 800000000 --sched-deadline \ 1000000000 --mmapfork 23 -t 20 done Reported-by: Hu Chunyu Suggested-by: Oleg Nesterov Suggested-by: Valentin Schneider Suggested-by: Peter Zijlstra Signed-off-by: Wander Lairson Costa Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20230614122323.37957-2-wander@redhat.com Signed-off-by: Sasha Levin

mm: Move mm_cachep initialization to mm_init()

2023-08-08T17:56:36Z

commit af80602799681c78f14fbe20b6185a56020dedee upstream. In order to allow using mm_alloc() much earlier, move initializing mm_cachep into mm_init(). Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20221025201057.751153381@infradead.org Signed-off-by: Greg Kroah-Hartman

x86/mm: Use mm_alloc() in poking_init()

2023-08-08T17:56:36Z

commit 3f4c8211d982099be693be9aa7d6fc4607dff290 upstream. Instead of duplicating init_mm, allocate a fresh mm. The advantage is that mm_alloc() has much simpler dependencies. Additionally it makes more conceptual sense, init_mm has no (and must not have) user state to duplicate. Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20221025201057.816175235@infradead.org Signed-off-by: Greg Kroah-Hartman

posix-timers: Ensure timer ID search-loop limit is valid

2023-07-27T06:37:42Z

[ Upstream commit 8ce8849dd1e78dadcee0ec9acbd259d239b7069f ] posix_timer_add() tries to allocate a posix timer ID by starting from the cached ID which was stored by the last successful allocation. This is done in a loop searching the ID space for a free slot one by one. The loop has to terminate when the search wrapped around to the starting point. But that's racy vs. establishing the starting point. That is read out lockless, which leads to the following problem: CPU0 CPU1 posix_timer_add() start = sig->posix_timer_id; lock(hash_lock); ... posix_timer_add() if (++sig->posix_timer_id < 0) start = sig->posix_timer_id; sig->posix_timer_id = 0; So CPU1 can observe a negative start value, i.e. -1, and the loop break never happens because the condition can never be true: if (sig->posix_timer_id == start) break; While this is unlikely to ever turn into an endless loop as the ID space is huge (INT_MAX), the racy read of the start value caught the attention of KCSAN and Dmitry unearthed that incorrectness. Rewrite it so that all id operations are under the hash lock. Reported-by: syzbot+5c54bd3eb218bb595aa9@syzkaller.appspotmail.com Reported-by: Dmitry Vyukov Signed-off-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker Link: https://lore.kernel.org/r/87bkhzdn6g.ffs@tglx Signed-off-by: Sasha Levin

sched: Fix KCSAN noinstr violation

2023-05-30T11:44:04Z

[ Upstream commit e0b081d17a9f4e5c0cbb0e5fbeb1abe3de0f7e4e ] With KCSAN enabled, end_of_stack() can get out-of-lined. Force it inline. Fixes the following warnings: vmlinux.o: warning: objtool: check_stackleak_irqoff+0x2b: call to end_of_stack() leaves .noinstr.text section Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/cc1b4d73d3a428a00d206242a68fdf99a934ca7b.1681320026.git.jpoimboe@kernel.org Signed-off-by: Sasha Levin

exit: Add and use make_task_dead.

2023-02-06T06:52:49Z

commit 0e25498f8cd43c1b5aa327f373dd094e9a006da7 upstream. There are two big uses of do_exit. The first is it's design use to be the guts of the exit(2) system call. The second use is to terminate a task after something catastrophic has happened like a NULL pointer in kernel code. Add a function make_task_dead that is initialy exactly the same as do_exit to cover the cases where do_exit is called to handle catastrophic failure. In time this can probably be reduced to just a light wrapper around do_task_dead. For now keep it exactly the same so that there will be no behavioral differences introducing this new concept. Replace all of the uses of do_exit that use it for catastraphic task cleanup with make_task_dead to make it clear what the code is doing. As part of this rename rewind_stack_do_exit rewind_stack_and_make_dead. Signed-off-by: "Eric W. Biederman" Signed-off-by: Eric Biggers Signed-off-by: Sasha Levin

task_stack, x86/cea: Force-inline stack helpers

2022-09-28T09:03:57Z

[ Upstream commit e87f4152e542610d0b4c6c8548964a68a59d2040 ] Force-inline two stack helpers to fix the following objtool warnings: vmlinux.o: warning: objtool: in_task_stack()+0xc: call to task_stack_page() leaves .noinstr.text section vmlinux.o: warning: objtool: in_entry_stack()+0x10: call to cpu_entry_stack() leaves .noinstr.text section Signed-off-by: Borislav Petkov Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20220324183607.31717-2-bp@alien8.de Stable-dep-of: 54c3931957f6 ("tracing: hold caller_addr to hardirq_{enable,disable}_ip") Signed-off-by: Sasha Levin

mm, hugetlb: allow for "high" userspace addresses

2022-05-09T07:03:28Z

commit 5f24d5a579d1eace79d505b148808a850b417d4c upstream. This is a fix for commit f6795053dac8 ("mm: mmap: Allow for "high" userspace addresses") for hugetlb. This patch adds support for "high" userspace addresses that are optionally supported on the system and have to be requested via a hint mechanism ("high" addr parameter to mmap). Architectures such as powerpc and x86 achieve this by making changes to their architectural versions of hugetlb_get_unmapped_area() function. However, arm64 uses the generic version of that function. So take into account arch_get_mmap_base() and arch_get_mmap_end() in hugetlb_get_unmapped_area(). To allow that, move those two macros out of mm/mmap.c into include/linux/sched/mm.h If these macros are not defined in architectural code then they default to (TASK_SIZE) and (base) so should not introduce any behavioural changes to architectures that do not define them. For the time being, only ARM64 is affected by this change. Catalin (ARM64) said "We should have fixed hugetlb_get_unmapped_area() as well when we added support for 52-bit VA. The reason for commit f6795053dac8 was to prevent normal mmap() from returning addresses above 48-bit by default as some user-space had hard assumptions about this. It's a slight ABI change if you do this for hugetlb_get_unmapped_area() but I doubt anyone would notice. It's more likely that the current behaviour would cause issues, so I'd rather have them consistent. Basically when arm64 gained support for 52-bit addresses we did not want user-space calling mmap() to suddenly get such high addresses, otherwise we could have inadvertently broken some programs (similar behaviour to x86 here). Hence we added commit f6795053dac8. But we missed hugetlbfs which could still get such high mmap() addresses. So in theory that's a potential regression that should have bee addressed at the same time as commit f6795053dac8 (and before arm64 enabled 52-bit addresses)" Link: https://lkml.kernel.org/r/ab847b6edb197bffdfe189e70fb4ac76bfe79e0d.1650033747.git.christophe.leroy@csgroup.eu Fixes: f6795053dac8 ("mm: mmap: Allow for "high" userspace addresses") Signed-off-by: Christophe Leroy Reviewed-by: Catalin Marinas Cc: Steve Capper Cc: Will Deacon Cc: [5.0.x] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

shm: extend forced shm destroy to support objects from several IPC nses

2021-12-01T08:23:35Z

commit 85b6d24646e4125c591639841169baa98a2da503 upstream. Currently, the exit_shm() function not designed to work properly when task->sysvshm.shm_clist holds shm objects from different IPC namespaces. This is a real pain when sysctl kernel.shm_rmid_forced = 1, because it leads to use-after-free (reproducer exists). This is an attempt to fix the problem by extending exit_shm mechanism to handle shm's destroy from several IPC ns'es. To achieve that we do several things: 1. add a namespace (non-refcounted) pointer to the struct shmid_kernel 2. during new shm object creation (newseg()/shmget syscall) we initialize this pointer by current task IPC ns 3. exit_shm() fully reworked such that it traverses over all shp's in task->sysvshm.shm_clist and gets IPC namespace not from current task as it was before but from shp's object itself, then call shm_destroy(shp, ns). Note: We need to be really careful here, because as it was said before (1), our pointer to IPC ns non-refcnt'ed. To be on the safe side we using special helper get_ipc_ns_not_zero() which allows to get IPC ns refcounter only if IPC ns not in the "state of destruction". Q/A Q: Why can we access shp->ns memory using non-refcounted pointer? A: Because shp object lifetime is always shorther than IPC namespace lifetime, so, if we get shp object from the task->sysvshm.shm_clist while holding task_lock(task) nobody can steal our namespace. Q: Does this patch change semantics of unshare/setns/clone syscalls? A: No. It's just fixes non-covered case when process may leave IPC namespace without getting task->sysvshm.shm_clist list cleaned up. Link: https://lkml.kernel.org/r/67bb03e5-f79c-1815-e2bf-949c67047418@colorfullife.com Link: https://lkml.kernel.org/r/20211109151501.4921-1-manfred@colorfullife.com Fixes: ab602f79915 ("shm: make exit_shm work proportional to task activity") Co-developed-by: Manfred Spraul Signed-off-by: Manfred Spraul Signed-off-by: Alexander Mikhalitsyn Cc: "Eric W. Biederman" Cc: Davidlohr Bueso Cc: Greg KH Cc: Andrei Vagin Cc: Pavel Tikhomirov Cc: Vasily Averin Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

task_stack: Fix end_of_stack() for architectures with upwards-growing stack

2021-11-17T08:48:33Z

[ Upstream commit 9cc2fa4f4a92ccc6760d764e7341be46ee8aaaa1 ] The function end_of_stack() returns a pointer to the last entry of a stack. For architectures like parisc where the stack grows upwards return the pointer to the highest address in the stack. Without this change I faced a crash on parisc, because the stackleak functionality wrote STACKLEAK_POISON to the lowest address and thus overwrote the first 4 bytes of the task_struct which included the TIF_FLAGS. Signed-off-by: Helge Deller Signed-off-by: Sasha Levin