From 8a1115ff6b6d90cf1066ec3a0c4e51276553eebe Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 9 Mar 2017 16:16:31 -0800 Subject: scripts/spelling.txt: add "disble(d)" pattern and fix typo instances Fix typos and add the following to the scripts/spelling.txt: disble||disable disbled||disabled I kept the TSL2563_INT_DISBLED in /drivers/iio/light/tsl2563.c untouched. The macro is not referenced at all, but this commit is touching only comment blocks just in case. Link: http://lkml.kernel.org/r/1481573103-11329-20-git-send-email-yamada.masahiro@socionext.com Signed-off-by: Masahiro Yamada Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/cgroup/cgroup.c | 2 +- kernel/events/core.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 0125589c7428..48851327a15e 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -2669,7 +2669,7 @@ static bool css_visible(struct cgroup_subsys_state *css) * * Returns 0 on success, -errno on failure. On failure, csses which have * been processed already aren't cleaned up. The caller is responsible for - * cleaning up with cgroup_apply_control_disble(). + * cleaning up with cgroup_apply_control_disable(). */ static int cgroup_apply_control_enable(struct cgroup *cgrp) { diff --git a/kernel/events/core.c b/kernel/events/core.c index 6f41548f2e32..a17ed56c8ce1 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -998,7 +998,7 @@ list_update_cgroup_event(struct perf_event *event, */ #define PERF_CPU_HRTIMER (1000 / HZ) /* - * function must be called with interrupts disbled + * function must be called with interrupts disabled */ static enum hrtimer_restart perf_mux_hrtimer_handler(struct hrtimer *hr) { -- cgit v1.2.1 From 505d3085d7120a9f4cd0d6ffaa876968854b3baa Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 9 Mar 2017 16:16:33 -0800 Subject: scripts/spelling.txt: add "overide" pattern and fix typo instances Fix typos and add the following to the scripts/spelling.txt: overide||override While we are here, fix the doubled "address" in the touched line Documentation/devicetree/bindings/regulator/ti-abb-regulator.txt. Also, fix the comment block style in the touched hunks in drivers/media/dvb-frontends/drx39xyj/drx_driver.h. Link: http://lkml.kernel.org/r/1481573103-11329-21-git-send-email-yamada.masahiro@socionext.com Signed-off-by: Masahiro Yamada Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/trace/trace_stack.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c index 1d68b5b7ad41..5fb1f2c87e6b 100644 --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -65,7 +65,7 @@ void stack_trace_print(void) } /* - * When arch-specific code overides this function, the following + * When arch-specific code overrides this function, the following * data should be filled up, assuming stack_trace_max_lock is held to * prevent concurrent updates. * stack_trace_index[] -- cgit v1.2.1 From dd0db88d8094a6d9d4d1fc5fcd56ab619f54ccf8 Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Thu, 9 Mar 2017 16:16:49 -0800 Subject: userfaultfd: non-cooperative: rollback userfaultfd_exit Patch series "userfaultfd non-cooperative further update for 4.11 merge window". Unfortunately I noticed one relevant bug in userfaultfd_exit while doing more testing. I've been doing testing before and this was also tested by kbuild bot and exercised by the selftest, but this bug never reproduced before. I dropped userfaultfd_exit as result. I dropped it because of implementation difficulty in receiving signals in __mmput and because I think -ENOSPC as result from the background UFFDIO_COPY should be enough already. Before I decided to remove userfaultfd_exit, I noticed userfaultfd_exit wasn't exercised by the selftest and when I tried to exercise it, after moving it to a more correct place in __mmput where it would make more sense and where the vma list is stable, it resulted in the event_wait_completion in D state. So then I added the second patch to be sure even if we call userfaultfd_event_wait_completion too late during task exit(), we won't risk to generate tasks in D state. The same check exists in handle_userfault() for the same reason, except it makes a difference there, while here is just a robustness check and it's run under WARN_ON_ONCE. While looking at the userfaultfd_event_wait_completion() function I looked back at its callers too while at it and I think it's not ok to stop executing dup_fctx on the fcs list because we relay on userfaultfd_event_wait_completion to execute userfaultfd_ctx_put(fctx->orig) which is paired against userfaultfd_ctx_get(fctx->orig) in dup_userfault just before list_add(fcs). This change only takes care of fctx->orig but this area also needs further review looking for similar problems in fctx->new. The only patch that is urgent is the first because it's an use after free during a SMP race condition that affects all processes if CONFIG_USERFAULTFD=y. Very hard to reproduce though and probably impossible without SLUB poisoning enabled. This patch (of 3): I once reproduced this oops with the userfaultfd selftest, it's not easily reproducible and it requires SLUB poisoning to reproduce. general protection fault: 0000 [#1] SMP Modules linked in: CPU: 2 PID: 18421 Comm: userfaultfd Tainted: G ------------ T 3.10.0+ #15 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.10.1-0-g8891697-prebuilt.qemu-project.org 04/01/2014 task: ffff8801f83b9440 ti: ffff8801f833c000 task.ti: ffff8801f833c000 RIP: 0010:[] [] userfaultfd_exit+0x29/0xa0 RSP: 0018:ffff8801f833fe80 EFLAGS: 00010202 RAX: ffff8801f833ffd8 RBX: 6b6b6b6b6b6b6b6b RCX: ffff8801f83b9440 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8800baf18600 RBP: ffff8801f833fee8 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000000 R11: ffffffff8127ceb3 R12: 0000000000000000 R13: ffff8800baf186b0 R14: ffff8801f83b99f8 R15: 00007faed746c700 FS: 0000000000000000(0000) GS:ffff88023fc80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00007faf0966f028 CR3: 0000000001bc6000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: do_exit+0x297/0xd10 SyS_exit+0x17/0x20 tracesys+0xdd/0xe2 Code: 00 00 66 66 66 66 90 55 48 89 e5 41 54 53 48 83 ec 58 48 8b 1f 48 85 db 75 11 eb 73 66 0f 1f 44 00 00 48 8b 5b 10 48 85 db 74 64 <4c> 8b a3 b8 00 00 00 4d 85 e4 74 eb 41 f6 84 24 2c 01 00 00 80 RIP [] userfaultfd_exit+0x29/0xa0 RSP ---[ end trace 9fecd6dcb442846a ]--- In the debugger I located the "mm" pointer in the stack and walking mm->mmap->vm_next through the end shows the vma->vm_next list is fully consistent and it is null terminated list as expected. So this has to be an SMP race condition where userfaultfd_exit was running while the vma list was being modified by another CPU. When userfaultfd_exit() run one of the ->vm_next pointers pointed to SLAB_POISON (RBX is the vma pointer and is 0x6b6b..). The reason is that it's not running in __mmput but while there are still other threads running and it's not holding the mmap_sem (it can't as it has to wait the even to be received by the manager). So this is an use after free that was happening for all processes. One more implementation problem aside from the race condition: userfaultfd_exit has really to check a flag in mm->flags before walking the vma or it's going to slowdown the exit() path for regular tasks. One more implementation problem: at that point signals can't be delivered so it would also create a task in D state if the manager doesn't read the event. The major design issue: it overall looks superfluous as the manager can check for -ENOSPC in the background transfer: if (mmget_not_zero(ctx->mm)) { [..] } else { return -ENOSPC; } It's safer to roll it back and re-introduce it later if at all. [rppt@linux.vnet.ibm.com: documentation fixup after removal of UFFD_EVENT_EXIT] Link: http://lkml.kernel.org/r/1488345437-4364-1-git-send-email-rppt@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/20170224181957.19736-2-aarcange@redhat.com Signed-off-by: Andrea Arcangeli Signed-off-by: Mike Rapoport Acked-by: Mike Rapoport Cc: "Dr. David Alan Gilbert" Cc: Mike Kravetz Cc: Pavel Emelyanov Cc: Hillf Danton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/exit.c | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel') diff --git a/kernel/exit.c b/kernel/exit.c index e126ebf2400c..516acdb0e0ec 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -554,7 +554,6 @@ static void exit_mm(void) enter_lazy_tlb(mm, current); task_unlock(current); mm_update_next_owner(mm); - userfaultfd_exit(mm); mmput(mm); if (test_thread_flag(TIF_MEMDIE)) exit_oom_victim(); -- cgit v1.2.1