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9899d11f65
linux/arch/x86/kernel
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Oleg Nesterov 9899d11f65 ptrace: ensure arch_ptrace/ptrace_request can never race with SIGKILL 
putreg() assumes that the tracee is not running and pt_regs_access() can
safely play with its stack.  However a killed tracee can return from
ptrace_stop() to the low-level asm code and do RESTORE_REST, this means
that debugger can actually read/modify the kernel stack until the tracee
does SAVE_REST again.

set_task_blockstep() can race with SIGKILL too and in some sense this
race is even worse, the very fact the tracee can be woken up breaks the
logic.

As Linus suggested we can clear TASK_WAKEKILL around the arch_ptrace()
call, this ensures that nobody can ever wakeup the tracee while the
debugger looks at it.  Not only this fixes the mentioned problems, we
can do some cleanups/simplifications in arch_ptrace() paths.

Probably ptrace_unfreeze_traced() needs more callers, for example it
makes sense to make the tracee killable for oom-killer before
access_process_vm().

While at it, add the comment into may_ptrace_stop() to explain why
ptrace_stop() still can't rely on SIGKILL and signal_pending_state().

Reported-by: Salman Qazi <sqazi@google.com>
Reported-by: Suleiman Souhlal <suleiman@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-01-22 10:08:00 -08:00
..
acpi Merge branch 'x86-acpi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-12-14 10:03:23 -08:00
apic PCI changes for the v3.8 merge window: 2012-12-13 12:14:47 -08:00
cpu X86: drivers: remove __dev* attributes. 2013-01-03 15:57:04 -08:00
.gitignore
alternative.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-10-01 10:47:45 -07:00
amd_gart_64.c X86 & IA64: adapt for dma_map_ops changes 2012-03-28 16:36:31 +02:00
amd_nb.c Merge branch 'x86-mce-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-07-22 16:07:45 -07:00
apb_timer.c Merge branch 'timers-clocksource-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-07-23 10:34:47 -07:00
aperture_64.c x86/gart: Fix kmemleak warning 2012-06-06 11:58:38 +02:00
apm_32.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
asm-offsets_32.c x86: Generate system call tables and unistd_*.h from tables 2011-11-17 13:35:37 -08:00
asm-offsets_64.c x32: If configured, add x32 system calls to system call tables 2012-02-20 12:52:06 -08:00
asm-offsets.c x86, um/x86: switch to generic sys_execve and kernel_execve 2012-09-30 22:53:32 -04:00
audit_64.c
bootflag.c
check.c x86: kernel/check.c simple_strtoul cleanup 2012-05-15 15:36:41 -07:00
cpuid.c Use get_online_cpus to avoid races involving CPU hotplug 2012-09-23 07:43:56 -07:00
crash_dump_32.c x86: remove the second argument of k[un]map_atomic() 2012-03-20 21:48:15 +08:00
crash_dump_64.c
crash.c x86/kexec: crash_vmclear_local_vmcss needs __rcu 2012-12-11 19:55:23 -02:00
devicetree.c x86: dt: Use linear irq domain for ioapic(s) 2012-08-21 22:16:57 +02:00
doublefault_32.c
dumpstack_32.c x86: Move call to print_modules() out of show_regs() 2012-06-20 14:33:48 +02:00
dumpstack_64.c x86: Move call to print_modules() out of show_regs() 2012-06-20 14:33:48 +02:00
dumpstack.c x86: Move call to print_modules() out of show_regs() 2012-06-20 14:33:48 +02:00
e820.c x86, mm: Trim memory in memblock to be page aligned 2012-10-24 11:52:21 -07:00
early_printk.c Revert "x86/early_printk: Replace obsolete simple_strtoul() usage with kstrtoint()" 2012-07-22 15:47:52 +02:00
early-quirks.c
entry_32.S Fixes: 2013-01-18 12:02:52 -08:00
entry_64.S Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal 2012-12-20 18:05:28 -08:00
ftrace.c ftrace/x86: Add save_regs for i386 function calls 2012-07-19 13:20:37 -04:00
head32.c x86, realmode: Move ACPI wakeup to unified realmode code 2012-05-08 11:46:05 -07:00
head64.c x86, realmode: Move ACPI wakeup to unified realmode code 2012-05-08 11:46:05 -07:00
head_32.S Merge branch 'x86-bsp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-12-11 19:56:33 -08:00
head_64.S x86-64, hotplug: Add start_cpu0() entry point to head_64.S 2012-11-14 09:39:51 -08:00
head.c memblock, x86: Replace memblock_x86_reserve/free_range() with generic ones 2011-07-14 11:47:53 -07:00
hpet.c x86: hpet: Fix masking of MSI interrupts 2012-11-02 22:53:27 +01:00
hw_breakpoint.c
i386_ksyms_32.c
i387.c x86/i387.c: Initialize thread xstate only on CPU0 only once 2012-11-14 15:28:11 -08:00
i8237.c
i8253.c x86: Use common i8253 clockevent 2011-07-01 10:37:14 +02:00
i8259.c x86/irq/i8259: Fix incorrect comment 2012-08-22 09:34:24 +02:00
io_delay.c
ioport.c
irq_32.c x86: Use common threadinfo allocator 2012-05-08 14:08:44 +02:00
irq_64.c x86: Add stack top margin for stack overflow checking 2011-12-07 09:27:11 +01:00
irq_work.c
irq.c Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-10-01 11:13:33 -07:00
irqinit.c x86, 386 removal: Remove support for IRQ 13 FPU error reporting 2012-12-17 11:42:40 -08:00
jump_label.c jump_label, x86: Fix section mismatch 2011-12-06 20:41:02 +01:00
kdebugfs.c arch/x86/kernel/kdebugfs.c: Ensure a consistent return value in error case 2012-07-26 15:07:20 +02:00
kgdb.c kgdb,x86: fix warning about unused variable 2012-10-12 06:37:34 -05:00
kprobes-common.h x86/kprobes: Split out optprobe related code to kprobes-opt.c 2012-03-06 09:49:49 +01:00
kprobes-opt.c x86/kprobes: Split out optprobe related code to kprobes-opt.c 2012-03-06 09:49:49 +01:00
kprobes.c kprobes/x86: Move skip_singlestep up 2012-09-20 14:48:16 +02:00
kvm.c Add rcu user eqs exception hooks for async page fault 2012-12-18 15:15:41 +02:00
kvmclock.c x86: kvm guest: pvclock vsyscall support 2012-11-27 23:29:10 -02:00
ldt.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
machine_kexec_32.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
machine_kexec_64.c
Makefile tracing,x86: Add a TSC trace_clock 2012-11-13 15:48:27 -05:00
microcode_amd.c x86, microcode, AMD: Add support for family 16h processors 2012-11-20 22:23:28 -08:00
microcode_core.c Merge branch 'x86-microcode-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-10-01 11:15:17 -07:00
microcode_intel.c x86, microcode: Add a refresh firmware flag to ->request_microcode_fw 2012-08-22 16:15:58 -07:00
mmconf-fam10h_64.c
module.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-07-24 13:34:56 -07:00
mpparse.c Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-05-29 20:14:53 -07:00
msr.c Use get_online_cpus to avoid races involving CPU hotplug 2012-09-23 07:43:56 -07:00
nmi_selftest.c x86/nmi: Clean up register_nmi_handler() usage 2012-06-20 14:23:17 +02:00
nmi.c x86: Save cr2 in NMI in case NMIs take a page fault (for i386) 2012-06-08 18:51:12 -04:00
paravirt_patch_32.c
paravirt_patch_64.c
paravirt-spinlocks.c
paravirt.c x86, pvops: Remove hooks for {rd,wr}msr_safe_regs 2012-06-07 11:41:08 -07:00
pci-calgary_64.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
pci-dma.c X86: drivers: remove __dev* attributes. 2013-01-03 15:57:04 -08:00
pci-iommu_table.c
pci-nommu.c X86: integrate CMA with DMA-mapping subsystem 2012-05-21 15:09:38 +02:00
pci-swiotlb.c X86 & IA64: adapt for dma_map_ops changes 2012-03-28 16:36:31 +02:00
pcspeaker.c
perf_regs.c perf: Fix off by one test in perf_reg_value() 2012-09-19 17:08:40 +02:00
probe_roms.c x86/pci/probe_roms: Add missing __iomem annotation to pci_map_biosrom() 2012-09-05 10:52:25 +02:00
process_32.c flagday: don't pass regs to copy_thread() 2012-11-28 23:43:42 -05:00
process_64.c flagday: don't pass regs to copy_thread() 2012-11-28 23:43:42 -05:00
process.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal 2012-12-12 12:22:13 -08:00
ptrace.c Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu 2012-12-03 06:27:05 +01:00
pvclock.c x86: pvclock: generic pvclock vsyscall initialization 2012-11-27 23:29:09 -02:00
quirks.c X86: drivers: remove __dev* attributes. 2013-01-03 15:57:04 -08:00
reboot_fixups_32.c
reboot.c x86/reboot: Remove quirk entry for SBC FITPC 2012-10-04 12:22:32 +02:00
relocate_kernel_32.S kexec, x86: Fix incorrect jump back address if not preserving context 2011-07-21 11:19:28 +02:00
relocate_kernel_64.S kexec, x86: Fix incorrect jump back address if not preserving context 2011-07-21 11:19:28 +02:00
resource.c
rtc.c x86: Allow tracing of functions in arch/x86/kernel/rtc.c 2012-10-24 13:14:22 +02:00
setup_percpu.c x86: Add read_mostly declaration/definition to variables from smp.h 2012-06-14 12:42:11 +02:00
setup.c x86/Sandy Bridge: Sandy Bridge workaround depends on CONFIG_PCI 2013-01-13 20:58:57 -08:00
signal.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal 2012-12-20 18:05:28 -08:00
smp.c x86/reboot: Update nonmi_ipi parameter 2012-05-14 11:49:38 +02:00
smpboot.c Merge branch 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-12-11 19:58:29 -08:00
stacktrace.c x86: Swap save_stack_trace_regs parameters 2011-06-14 22:48:51 -04:00
step.c ptrace: ensure arch_ptrace/ptrace_request can never race with SIGKILL 2013-01-22 10:08:00 -08:00
sys_x86_64.c mm: fix cache coloring on x86_64 architecture 2012-12-11 17:22:25 -08:00
syscall_32.c x86, syscall: Re-fix typo in comment 2011-11-18 16:25:07 -08:00
syscall_64.c x32: If configured, add x32 system calls to system call tables 2012-02-20 12:52:06 -08:00
tboot.c Revert "x86-64/efi: Use EFI to deal with platform wall clock (again)" 2012-12-15 15:20:41 -08:00
tce_64.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
test_nx.c
test_rodata.c x86, extable: Remove open-coded exception table entries in arch/x86/kernel/test_rodata.c 2012-04-20 13:51:38 -07:00
time.c MCA: delete all remaining traces of microchannel bus support. 2012-05-17 19:06:13 -04:00
tls.c Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 14:28:26 -07:00
tls.h
topology.c x86, topology: Debug CPU0 hotplug 2012-11-14 15:28:11 -08:00
trace_clock.c tracing,x86: Add a TSC trace_clock 2012-11-13 15:48:27 -05:00
traps.c Merge branch 'x86/nuke386' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-12-19 13:02:23 -08:00
tsc_sync.c x86/tsc: Reduce the TSC sync check time for core-siblings 2012-02-22 11:49:40 +01:00
tsc.c x86: Allow tracing of functions in arch/x86/kernel/rtc.c 2012-10-24 13:14:22 +02:00
uprobes.c uprobes/x86: Cleanup the single-stepping code 2012-11-03 17:15:12 +01:00
verify_cpu.S
vm86_32.c thp: change split_huge_page_pmd() interface 2012-12-12 17:38:31 -08:00
vmlinux.lds.S x86, realmode: Move ACPI wakeup to unified realmode code 2012-05-08 11:46:05 -07:00
vsmp_64.c x86/apic/x2apic: Limit the vector reservation to the user specified mask 2012-07-06 11:00:22 +02:00
vsyscall_64.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2012-12-16 15:40:50 -08:00
vsyscall_emu_64.S x86-64: Rework vsyscall emulation and add vsyscall= parameter 2011-08-10 19:26:46 -05:00
vsyscall_trace.h x86-64: Add vsyscall:emulate_vsyscall trace event 2011-08-04 16:13:53 -07:00
x86_init.c x86: xen: Cleanup and remove x86_init.paging.pagetable_setup_done() 2012-09-12 15:33:06 +02:00
x8664_ksyms_64.c ftrace/x86: Add support for -mfentry to x86_64 2012-08-23 11:26:36 -04:00
xsave.c x86, smap: Do not abuse the [f][x]rstor_checking() functions for user space 2012-09-25 15:42:18 -07:00