user/sven/linux.git/kernel/panic.c, branch v4.19.155

kernel/panic.c: do not append newline to the stack protector panic string

2019-12-01T08:17:10Z

[ Upstream commit 95c4fb78fb23081472465ca20d5d31c4b780ed82 ] ... because panic() itself already does this. Otherwise you have line-broken trailer: [ 1.836965] ---[ end Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: pgd_alloc+0x29e/0x2a0 [ 1.836965] ]--- Link: http://lkml.kernel.org/r/20181008202901.7894-1-bp@alien8.de Signed-off-by: Borislav Petkov Acked-by: Kees Cook Cc: Masahiro Yamada Cc: "Steven Rostedt (VMware)" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

panic: ensure preemption is disabled during panic()

2019-10-17T20:44:46Z

commit 20bb759a66be52cf4a9ddd17fddaf509e11490cd upstream. Calling 'panic()' on a kernel with CONFIG_PREEMPT=y can leave the calling CPU in an infinite loop, but with interrupts and preemption enabled. From this state, userspace can continue to be scheduled, despite the system being "dead" as far as the kernel is concerned. This is easily reproducible on arm64 when booting with "nosmp" on the command line; a couple of shell scripts print out a periodic "Ping" message whilst another triggers a crash by writing to /proc/sysrq-trigger: | sysrq: Trigger a crash | Kernel panic - not syncing: sysrq triggered crash | CPU: 0 PID: 1 Comm: init Not tainted 5.2.15 #1 | Hardware name: linux,dummy-virt (DT) | Call trace: | dump_backtrace+0x0/0x148 | show_stack+0x14/0x20 | dump_stack+0xa0/0xc4 | panic+0x140/0x32c | sysrq_handle_reboot+0x0/0x20 | __handle_sysrq+0x124/0x190 | write_sysrq_trigger+0x64/0x88 | proc_reg_write+0x60/0xa8 | __vfs_write+0x18/0x40 | vfs_write+0xa4/0x1b8 | ksys_write+0x64/0xf0 | __arm64_sys_write+0x14/0x20 | el0_svc_common.constprop.0+0xb0/0x168 | el0_svc_handler+0x28/0x78 | el0_svc+0x8/0xc | Kernel Offset: disabled | CPU features: 0x0002,24002004 | Memory Limit: none | ---[ end Kernel panic - not syncing: sysrq triggered crash ]--- | Ping 2! | Ping 1! | Ping 1! | Ping 2! The issue can also be triggered on x86 kernels if CONFIG_SMP=n, otherwise local interrupts are disabled in 'smp_send_stop()'. Disable preemption in 'panic()' before re-enabling interrupts. Link: http://lkml.kernel.org/r/20191002123538.22609-1-will@kernel.org Link: https://lore.kernel.org/r/BX1W47JXPMR8.58IYW53H6M5N@dragonstone Signed-off-by: Will Deacon Reported-by: Xogium Reviewed-by: Kees Cook Cc: Russell King Cc: Greg Kroah-Hartman Cc: Ingo Molnar Cc: Petr Mladek Cc: Feng Tang Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

panic: avoid deadlocks in re-entrant console drivers

2018-12-29T12:37:57Z

commit c7c3f05e341a9a2bd1a92993d4f996cfd6e7348e upstream. From printk()/serial console point of view panic() is special, because it may force CPU to re-enter printk() or/and serial console driver. Therefore, some of serial consoles drivers are re-entrant. E.g. 8250: serial8250_console_write() { if (port->sysrq) locked = 0; else if (oops_in_progress) locked = spin_trylock_irqsave(&port->lock, flags); else spin_lock_irqsave(&port->lock, flags); ... } panic() does set oops_in_progress via bust_spinlocks(1), so in theory we should be able to re-enter serial console driver from panic(): CPU0 uart_console_write() serial8250_console_write() // if (oops_in_progress) // spin_trylock_irqsave() call_console_drivers() console_unlock() console_flush_on_panic() bust_spinlocks(1) // oops_in_progress++ panic() spin_lock_irqsave(&port->lock, flags) // spin_lock_irqsave() serial8250_console_write() call_console_drivers() console_unlock() printk() ... However, this does not happen and we deadlock in serial console on port->lock spinlock. And the problem is that console_flush_on_panic() called after bust_spinlocks(0): void panic(const char *fmt, ...) { bust_spinlocks(1); ... bust_spinlocks(0); console_flush_on_panic(); ... } bust_spinlocks(0) decrements oops_in_progress, so oops_in_progress can go back to zero. Thus even re-entrant console drivers will simply spin on port->lock spinlock. Given that port->lock may already be locked either by a stopped CPU, or by the very same CPU we execute panic() on (for instance, NMI panic() on printing CPU) the system deadlocks and does not reboot. Fix this by removing bust_spinlocks(0), so oops_in_progress is always set in panic() now and, thus, re-entrant console drivers will trylock the port->lock instead of spinning on it forever, when we call them from console_flush_on_panic(). Link: http://lkml.kernel.org/r/20181025101036.6823-1-sergey.senozhatsky@gmail.com Cc: Steven Rostedt Cc: Daniel Wang Cc: Peter Zijlstra Cc: Andrew Morton Cc: Linus Torvalds Cc: Greg Kroah-Hartman Cc: Alan Cox Cc: Jiri Slaby Cc: Peter Feiner Cc: linux-serial@vger.kernel.org Cc: Sergey Senozhatsky Cc: stable@vger.kernel.org Signed-off-by: Sergey Senozhatsky Signed-off-by: Petr Mladek Signed-off-by: Greg Kroah-Hartman

Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables

2018-06-14T03:21:18Z

The changes to automatically test for working stack protector compiler support in the Kconfig files removed the special STACKPROTECTOR_AUTO option that picked the strongest stack protector that the compiler supported. That was all a nice cleanup - it makes no sense to have the AUTO case now that the Kconfig phase can just determine the compiler support directly. HOWEVER. It also meant that doing "make oldconfig" would now _disable_ the strong stackprotector if you had AUTO enabled, because in a legacy config file, the sane stack protector configuration would look like CONFIG_HAVE_CC_STACKPROTECTOR=y # CONFIG_CC_STACKPROTECTOR_NONE is not set # CONFIG_CC_STACKPROTECTOR_REGULAR is not set # CONFIG_CC_STACKPROTECTOR_STRONG is not set CONFIG_CC_STACKPROTECTOR_AUTO=y and when you ran this through "make oldconfig" with the Kbuild changes, it would ask you about the regular CONFIG_CC_STACKPROTECTOR (that had been renamed from CONFIG_CC_STACKPROTECTOR_REGULAR to just CONFIG_CC_STACKPROTECTOR), but it would think that the STRONG version used to be disabled (because it was really enabled by AUTO), and would disable it in the new config, resulting in: CONFIG_HAVE_CC_STACKPROTECTOR=y CONFIG_CC_HAS_STACKPROTECTOR_NONE=y CONFIG_CC_STACKPROTECTOR=y # CONFIG_CC_STACKPROTECTOR_STRONG is not set CONFIG_CC_HAS_SANE_STACKPROTECTOR=y That's dangerously subtle - people could suddenly find themselves with the weaker stack protector setup without even realizing. The solution here is to just rename not just the old RECULAR stack protector option, but also the strong one. This does that by just removing the CC_ prefix entirely for the user choices, because it really is not about the compiler support (the compiler support now instead automatially impacts _visibility_ of the options to users). This results in "make oldconfig" actually asking the user for their choice, so that we don't have any silent subtle security model changes. The end result would generally look like this: CONFIG_HAVE_CC_STACKPROTECTOR=y CONFIG_CC_HAS_STACKPROTECTOR_NONE=y CONFIG_STACKPROTECTOR=y CONFIG_STACKPROTECTOR_STRONG=y CONFIG_CC_HAS_SANE_STACKPROTECTOR=y where the "CC_" versions really are about internal compiler infrastructure, not the user selections. Acked-by: Masahiro Yamada Signed-off-by: Linus Torvalds

taint: add taint for randstruct

2018-04-11T17:28:35Z

Since the randstruct plugin can intentionally produce extremely unusual kernel structure layouts (even performance pathological ones), some maintainers want to be able to trivially determine if an Oops is coming from a randstruct-built kernel, so as to keep their sanity when debugging. This adds the new flag and initializes taint_mask immediately when built with randstruct. Link: http://lkml.kernel.org/r/1519084390-43867-4-git-send-email-keescook@chromium.org Signed-off-by: Kees Cook Reviewed-by: Andrew Morton Cc: Al Viro Cc: Alexey Dobriyan Cc: Jonathan Corbet Cc: Randy Dunlap Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

taint: consolidate documentation

2018-04-11T17:28:34Z

This consolidates the taint bit documentation into a single place with both numeric and letter values. Additionally adds the missing TAINT_AUX documentation. Link: http://lkml.kernel.org/r/1519084390-43867-3-git-send-email-keescook@chromium.org Signed-off-by: Kees Cook Reviewed-by: Andrew Morton Cc: Al Viro Cc: Alexey Dobriyan Cc: Jonathan Corbet Cc: Randy Dunlap Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

taint: convert to indexed initialization

2018-04-11T17:28:34Z

This converts to using indexed initializers instead of comments, adds a comment on why the taint flags can't be an enum, and make sure that no one forgets to update the taint_flags when adding new bits. Link: http://lkml.kernel.org/r/1519084390-43867-2-git-send-email-keescook@chromium.org Signed-off-by: Kees Cook Reviewed-by: Andrew Morton Cc: Al Viro Cc: Alexey Dobriyan Cc: Jonathan Corbet Cc: Randy Dunlap Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'trace-v4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2018-04-10T18:27:30Z

Pull tracing updates from Steven Rostedt: "New features: - Tom Zanussi's extended histogram work. This adds the synthetic events to have histograms from multiple event data Adds triggers "onmatch" and "onmax" to call the synthetic events Several updates to the histogram code from this - Allow way to nest ring buffer calls in the same context - Allow absolute time stamps in ring buffer - Rewrite of filter code parsing based on Al Viro's suggestions - Setting of trace_clock to global if TSC is unstable (on boot) - Better OOM handling when allocating large ring buffers - Added initcall tracepoints (consolidated initcall_debug code with them) And other various fixes and clean ups" * tag 'trace-v4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (68 commits) init: Have initcall_debug still work without CONFIG_TRACEPOINTS init, tracing: Have printk come through the trace events for initcall_debug init, tracing: instrument security and console initcall trace events init, tracing: Add initcall trace events tracing: Add rcu dereference annotation for test func that touches filter->prog tracing: Add rcu dereference annotation for filter->prog tracing: Fixup logic inversion on setting trace_global_clock defaults tracing: Hide global trace clock from lockdep ring-buffer: Add set/clear_current_oom_origin() during allocations ring-buffer: Check if memory is available before allocation lockdep: Add print_irqtrace_events() to __warn vsprintf: Do not preprocess non-dereferenced pointers for bprintf (%px and %pK) tracing: Uninitialized variable in create_tracing_map_fields() tracing: Make sure variable string fields are NULL-terminated tracing: Add action comparisons when testing matching hist triggers tracing: Don't add flag strings when displaying variable references tracing: Fix display of hist trigger expressions containing timestamps ftrace: Drop a VLA in module_exists() tracing: Mention trace_clock=global when warning about unstable clocks tracing: Default to using trace_global_clock if sched_clock is unstable ...

lockdep: Add print_irqtrace_events() to __warn

2018-04-06T12:56:51Z

Running a test on a x86_32 kernel I triggered a bug that an interrupt disable/enable isn't being catched by lockdep. At least knowing where the last one was found would be helpful, but the warnings that are produced do not show this information. Even without debugging lockdep, having the WARN() display the last place hard and soft irqs were enabled or disabled is valuable. Signed-off-by: Steven Rostedt (VMware)

Merge branch 'core-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2018-04-02T16:08:26Z

Pull misc core updates from Ingo Molnar: "Two changes: - add membarriers to Documentation/features/ - fix a minor nit in panic printk formatting" * 'core-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: panic: Add closing panic marker parenthesis Documentation/features, membarriers: Document membarrier-sync-core architecture support Documentation/features: Allow comments in arch features files