| Message ID | 20191122112621.204798-25-glider@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add KernelMemorySanitizer infrastructure | expand |
On Fri, Nov 22, 2019 at 12:27 PM <glider@google.com> wrote: > > Some functions are called from handwritten assembly, and therefore don't > have their arguments' metadata fully set up by the instrumentation code. > Mark them with __no_sanitize_memory to avoid false positives from > spreading further. > Certain functions perform task switching, so that the value of |current| > is different as they proceed. Because KMSAN state pointer is only read > once at the beginning of the function, touching it after |current| has > changed may be dangerous. > > Signed-off-by: Alexander Potapenko <glider@google.com> > To: Alexander Potapenko <glider@google.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Vegard Nossum <vegard.nossum@oracle.com> > Cc: Dmitry Vyukov <dvyukov@google.com> > Cc: linux-mm@kvack.org > --- > v3: > - removed TODOs from comments > > Change-Id: I684d23dac5a22eb0a4cea71993cb934302b17cea > --- > arch/x86/entry/common.c | 1 + > arch/x86/include/asm/irq_regs.h | 1 + > arch/x86/include/asm/syscall_wrapper.h | 1 + > arch/x86/kernel/apic/apic.c | 1 + > arch/x86/kernel/dumpstack_64.c | 1 + > arch/x86/kernel/process_64.c | 5 +++++ > arch/x86/kernel/traps.c | 12 ++++++++++-- > arch/x86/kernel/uprobes.c | 7 ++++++- > kernel/profile.c | 1 + > kernel/sched/core.c | 6 ++++++ > 10 files changed, 33 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c > index 3f8e22615812..0dd5b2acb355 100644 > --- a/arch/x86/entry/common.c > +++ b/arch/x86/entry/common.c > @@ -275,6 +275,7 @@ __visible inline void syscall_return_slowpath(struct pt_regs *regs) > } > > #ifdef CONFIG_X86_64 > +__no_sanitize_memory > __visible void do_syscall_64(unsigned long nr, struct pt_regs *regs) > { > struct thread_info *ti; > diff --git a/arch/x86/include/asm/irq_regs.h b/arch/x86/include/asm/irq_regs.h > index 187ce59aea28..d65a00bd6f02 100644 > --- a/arch/x86/include/asm/irq_regs.h > +++ b/arch/x86/include/asm/irq_regs.h > @@ -14,6 +14,7 @@ > > DECLARE_PER_CPU(struct pt_regs *, irq_regs); > > +__no_sanitize_memory > static inline struct pt_regs *get_irq_regs(void) > { > return __this_cpu_read(irq_regs); > diff --git a/arch/x86/include/asm/syscall_wrapper.h b/arch/x86/include/asm/syscall_wrapper.h > index e046a405743d..43910ce1b53b 100644 > --- a/arch/x86/include/asm/syscall_wrapper.h > +++ b/arch/x86/include/asm/syscall_wrapper.h > @@ -159,6 +159,7 @@ > ALLOW_ERROR_INJECTION(__x64_sys##name, ERRNO); \ > static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ > static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\ > + __no_sanitize_memory \ > asmlinkage long __x64_sys##name(const struct pt_regs *regs) \ > { \ > return __se_sys##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\ > diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c > index 9e2dd2b296cd..7b24bda22c38 100644 > --- a/arch/x86/kernel/apic/apic.c > +++ b/arch/x86/kernel/apic/apic.c > @@ -1118,6 +1118,7 @@ static void local_apic_timer_interrupt(void) > * [ if a single-CPU system runs an SMP kernel then we call the local > * interrupt as well. Thus we cannot inline the local irq ... ] > */ > +__no_sanitize_memory /* |regs| may be uninitialized */ The comment style around __no_sanitize_memory looks very different for different call sites, perhaps it makes sense to unify it somehow. > __visible void __irq_entry smp_apic_timer_interrupt(struct pt_regs *regs) > { > struct pt_regs *old_regs = set_irq_regs(regs); > diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c > index 753b8cfe8b8a..ba883d282a43 100644 > --- a/arch/x86/kernel/dumpstack_64.c > +++ b/arch/x86/kernel/dumpstack_64.c > @@ -143,6 +143,7 @@ static bool in_irq_stack(unsigned long *stack, struct stack_info *info) > return true; > } > > +__no_sanitize_memory > int get_stack_info(unsigned long *stack, struct task_struct *task, > struct stack_info *info, unsigned long *visit_mask) > { > diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c > index af64519b2695..70e33150a83a 100644 > --- a/arch/x86/kernel/process_64.c > +++ b/arch/x86/kernel/process_64.c > @@ -500,6 +500,11 @@ void compat_start_thread(struct pt_regs *regs, u32 new_ip, u32 new_sp) > * Kprobes not supported here. Set the probe on schedule instead. > * Function graph tracer not supported too. > */ > +/* > + * Avoid touching KMSAN state or reporting anything here, as __switch_to() does > + * weird things with tasks. > + */ > +__no_sanitize_memory > __visible __notrace_funcgraph struct task_struct * > __switch_to(struct task_struct *prev_p, struct task_struct *next_p) > { > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c > index 4bb0f8447112..a94282d1f60b 100644 > --- a/arch/x86/kernel/traps.c > +++ b/arch/x86/kernel/traps.c > @@ -618,7 +618,10 @@ NOKPROBE_SYMBOL(do_int3); > * Help handler running on a per-cpu (IST or entry trampoline) stack > * to switch to the normal thread stack if the interrupted code was in > * user mode. The actual stack switch is done in entry_64.S > + * > + * This function switches the registers - don't instrument it with KMSAN! > */ > +__no_sanitize_memory > asmlinkage __visible notrace struct pt_regs *sync_regs(struct pt_regs *eregs) > { > struct pt_regs *regs = (struct pt_regs *)this_cpu_read(cpu_current_top_of_stack) - 1; > @@ -634,6 +637,11 @@ struct bad_iret_stack { > }; > > asmlinkage __visible notrace > +/* > + * Dark magic happening here, let's not instrument this function. > + * Also avoid copying any metadata by using raw __memmove(). > + */ > +__no_sanitize_memory > struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s) > { > /* > @@ -648,10 +656,10 @@ struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s) > (struct bad_iret_stack *)this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1; > > /* Copy the IRET target to the new stack. */ > - memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8); > + __memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8); > > /* Copy the remainder of the stack from the current stack. */ > - memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip)); > + __memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip)); Looks like this change should go into a separate patch. > > BUG_ON(!user_mode(&new_stack->regs)); > return new_stack; > diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c > index 8cd745ef8c7b..bcd4bf5a909f 100644 > --- a/arch/x86/kernel/uprobes.c > +++ b/arch/x86/kernel/uprobes.c > @@ -8,6 +8,7 @@ > * Jim Keniston > */ > #include <linux/kernel.h> > +#include <linux/kmsan-checks.h> > #include <linux/sched.h> > #include <linux/ptrace.h> > #include <linux/uprobes.h> > @@ -997,9 +998,13 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) > int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data) > { > struct die_args *args = data; > - struct pt_regs *regs = args->regs; > + struct pt_regs *regs; > int ret = NOTIFY_DONE; > > + kmsan_unpoison_shadow(args, sizeof(*args)); > + regs = args->regs; > + if (regs) > + kmsan_unpoison_shadow(regs, sizeof(*regs)); This one as well. > /* We are only interested in userspace traps */ > if (regs && !user_mode(regs)) > return NOTIFY_DONE; > diff --git a/kernel/profile.c b/kernel/profile.c > index af7c94bf5fa1..835a5b66d1a4 100644 > --- a/kernel/profile.c > +++ b/kernel/profile.c > @@ -399,6 +399,7 @@ void profile_hits(int type, void *__pc, unsigned int nr_hits) > } > EXPORT_SYMBOL_GPL(profile_hits); > > +__no_sanitize_memory > void profile_tick(int type) > { > struct pt_regs *regs = get_irq_regs(); > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index dd05a378631a..674d36fe9d44 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -475,6 +475,7 @@ void wake_q_add_safe(struct wake_q_head *head, struct task_struct *task) > put_task_struct(task); > } > > +__no_sanitize_memory /* context switching here */ > void wake_up_q(struct wake_q_head *head) > { > struct wake_q_node *node = head->first; > @@ -3180,6 +3181,7 @@ prepare_task_switch(struct rq *rq, struct task_struct *prev, > * past. prev == current is still correct but we need to recalculate this_rq > * because prev may have moved to another CPU. > */ > +__no_sanitize_memory /* |current| changes here */ > static struct rq *finish_task_switch(struct task_struct *prev) > __releases(rq->lock) > { > @@ -3986,6 +3988,7 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) > * > * WARNING: must be called with preemption disabled! > */ > +__no_sanitize_memory /* |current| changes here */ > static void __sched notrace __schedule(bool preempt) > { > struct task_struct *prev, *next; > @@ -4605,6 +4608,7 @@ int task_prio(const struct task_struct *p) > * > * Return: 1 if the CPU is currently idle. 0 otherwise. > */ > +__no_sanitize_memory /* nothing to report here */ > int idle_cpu(int cpu) > { > struct rq *rq = cpu_rq(cpu); > @@ -6544,6 +6548,7 @@ static struct kmem_cache *task_group_cache __read_mostly; > DECLARE_PER_CPU(cpumask_var_t, load_balance_mask); > DECLARE_PER_CPU(cpumask_var_t, select_idle_mask); > > +__no_sanitize_memory > void __init sched_init(void) > { > unsigned long ptr = 0; > @@ -6716,6 +6721,7 @@ static inline int preempt_count_equals(int preempt_offset) > return (nested == preempt_offset); > } > > +__no_sanitize_memory /* expect the arguments to be initialized */ > void __might_sleep(const char *file, int line, int preempt_offset) > { > /* > -- > 2.24.0.432.g9d3f5f5b63-goog >
> The comment style around __no_sanitize_memory looks very different for > different call sites, perhaps it makes sense to unify it somehow. Done in v4. > > +/* > > + * Dark magic happening here, let's not instrument this function. > > + * Also avoid copying any metadata by using raw __memmove(). > > + */ > > +__no_sanitize_memory > > struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s) > > { > > /* > > @@ -648,10 +656,10 @@ struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s) > > (struct bad_iret_stack *)this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1; > > > > /* Copy the IRET target to the new stack. */ > > - memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8); > > + __memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8); > > > > /* Copy the remainder of the stack from the current stack. */ > > - memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip)); > > + __memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip)); > > Looks like this change should go into a separate patch. I disagree. Both the __no_sanitize_memory annotation and __memmove() calls serve the same purpose: avoid calling KMSAN code from fixup_bad_iret(). I don't think it makes sense to separate them. > > + kmsan_unpoison_shadow(args, sizeof(*args)); > > + regs = args->regs; > > + if (regs) > > + kmsan_unpoison_shadow(regs, sizeof(*regs)); > > This one as well. Done in v4.
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index 3f8e22615812..0dd5b2acb355 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -275,6 +275,7 @@ __visible inline void syscall_return_slowpath(struct pt_regs *regs) } #ifdef CONFIG_X86_64 +__no_sanitize_memory __visible void do_syscall_64(unsigned long nr, struct pt_regs *regs) { struct thread_info *ti; diff --git a/arch/x86/include/asm/irq_regs.h b/arch/x86/include/asm/irq_regs.h index 187ce59aea28..d65a00bd6f02 100644 --- a/arch/x86/include/asm/irq_regs.h +++ b/arch/x86/include/asm/irq_regs.h @@ -14,6 +14,7 @@ DECLARE_PER_CPU(struct pt_regs *, irq_regs); +__no_sanitize_memory static inline struct pt_regs *get_irq_regs(void) { return __this_cpu_read(irq_regs); diff --git a/arch/x86/include/asm/syscall_wrapper.h b/arch/x86/include/asm/syscall_wrapper.h index e046a405743d..43910ce1b53b 100644 --- a/arch/x86/include/asm/syscall_wrapper.h +++ b/arch/x86/include/asm/syscall_wrapper.h @@ -159,6 +159,7 @@ ALLOW_ERROR_INJECTION(__x64_sys##name, ERRNO); \ static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\ + __no_sanitize_memory \ asmlinkage long __x64_sys##name(const struct pt_regs *regs) \ { \ return __se_sys##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\ diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 9e2dd2b296cd..7b24bda22c38 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -1118,6 +1118,7 @@ static void local_apic_timer_interrupt(void) * [ if a single-CPU system runs an SMP kernel then we call the local * interrupt as well. Thus we cannot inline the local irq ... ] */ +__no_sanitize_memory /* |regs| may be uninitialized */ __visible void __irq_entry smp_apic_timer_interrupt(struct pt_regs *regs) { struct pt_regs *old_regs = set_irq_regs(regs); diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c index 753b8cfe8b8a..ba883d282a43 100644 --- a/arch/x86/kernel/dumpstack_64.c +++ b/arch/x86/kernel/dumpstack_64.c @@ -143,6 +143,7 @@ static bool in_irq_stack(unsigned long *stack, struct stack_info *info) return true; } +__no_sanitize_memory int get_stack_info(unsigned long *stack, struct task_struct *task, struct stack_info *info, unsigned long *visit_mask) { diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index af64519b2695..70e33150a83a 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -500,6 +500,11 @@ void compat_start_thread(struct pt_regs *regs, u32 new_ip, u32 new_sp) * Kprobes not supported here. Set the probe on schedule instead. * Function graph tracer not supported too. */ +/* + * Avoid touching KMSAN state or reporting anything here, as __switch_to() does + * weird things with tasks. + */ +__no_sanitize_memory __visible __notrace_funcgraph struct task_struct * __switch_to(struct task_struct *prev_p, struct task_struct *next_p) { diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 4bb0f8447112..a94282d1f60b 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -618,7 +618,10 @@ NOKPROBE_SYMBOL(do_int3); * Help handler running on a per-cpu (IST or entry trampoline) stack * to switch to the normal thread stack if the interrupted code was in * user mode. The actual stack switch is done in entry_64.S + * + * This function switches the registers - don't instrument it with KMSAN! */ +__no_sanitize_memory asmlinkage __visible notrace struct pt_regs *sync_regs(struct pt_regs *eregs) { struct pt_regs *regs = (struct pt_regs *)this_cpu_read(cpu_current_top_of_stack) - 1; @@ -634,6 +637,11 @@ struct bad_iret_stack { }; asmlinkage __visible notrace +/* + * Dark magic happening here, let's not instrument this function. + * Also avoid copying any metadata by using raw __memmove(). + */ +__no_sanitize_memory struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s) { /* @@ -648,10 +656,10 @@ struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s) (struct bad_iret_stack *)this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1; /* Copy the IRET target to the new stack. */ - memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8); + __memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8); /* Copy the remainder of the stack from the current stack. */ - memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip)); + __memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip)); BUG_ON(!user_mode(&new_stack->regs)); return new_stack; diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 8cd745ef8c7b..bcd4bf5a909f 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -8,6 +8,7 @@ * Jim Keniston */ #include <linux/kernel.h> +#include <linux/kmsan-checks.h> #include <linux/sched.h> #include <linux/ptrace.h> #include <linux/uprobes.h> @@ -997,9 +998,13 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data) { struct die_args *args = data; - struct pt_regs *regs = args->regs; + struct pt_regs *regs; int ret = NOTIFY_DONE; + kmsan_unpoison_shadow(args, sizeof(*args)); + regs = args->regs; + if (regs) + kmsan_unpoison_shadow(regs, sizeof(*regs)); /* We are only interested in userspace traps */ if (regs && !user_mode(regs)) return NOTIFY_DONE; diff --git a/kernel/profile.c b/kernel/profile.c index af7c94bf5fa1..835a5b66d1a4 100644 --- a/kernel/profile.c +++ b/kernel/profile.c @@ -399,6 +399,7 @@ void profile_hits(int type, void *__pc, unsigned int nr_hits) } EXPORT_SYMBOL_GPL(profile_hits); +__no_sanitize_memory void profile_tick(int type) { struct pt_regs *regs = get_irq_regs(); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index dd05a378631a..674d36fe9d44 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -475,6 +475,7 @@ void wake_q_add_safe(struct wake_q_head *head, struct task_struct *task) put_task_struct(task); } +__no_sanitize_memory /* context switching here */ void wake_up_q(struct wake_q_head *head) { struct wake_q_node *node = head->first; @@ -3180,6 +3181,7 @@ prepare_task_switch(struct rq *rq, struct task_struct *prev, * past. prev == current is still correct but we need to recalculate this_rq * because prev may have moved to another CPU. */ +__no_sanitize_memory /* |current| changes here */ static struct rq *finish_task_switch(struct task_struct *prev) __releases(rq->lock) { @@ -3986,6 +3988,7 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) * * WARNING: must be called with preemption disabled! */ +__no_sanitize_memory /* |current| changes here */ static void __sched notrace __schedule(bool preempt) { struct task_struct *prev, *next; @@ -4605,6 +4608,7 @@ int task_prio(const struct task_struct *p) * * Return: 1 if the CPU is currently idle. 0 otherwise. */ +__no_sanitize_memory /* nothing to report here */ int idle_cpu(int cpu) { struct rq *rq = cpu_rq(cpu); @@ -6544,6 +6548,7 @@ static struct kmem_cache *task_group_cache __read_mostly; DECLARE_PER_CPU(cpumask_var_t, load_balance_mask); DECLARE_PER_CPU(cpumask_var_t, select_idle_mask); +__no_sanitize_memory void __init sched_init(void) { unsigned long ptr = 0; @@ -6716,6 +6721,7 @@ static inline int preempt_count_equals(int preempt_offset) return (nested == preempt_offset); } +__no_sanitize_memory /* expect the arguments to be initialized */ void __might_sleep(const char *file, int line, int preempt_offset) { /*
Some functions are called from handwritten assembly, and therefore don't have their arguments' metadata fully set up by the instrumentation code. Mark them with __no_sanitize_memory to avoid false positives from spreading further. Certain functions perform task switching, so that the value of |current| is different as they proceed. Because KMSAN state pointer is only read once at the beginning of the function, touching it after |current| has changed may be dangerous. Signed-off-by: Alexander Potapenko <glider@google.com> To: Alexander Potapenko <glider@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: linux-mm@kvack.org --- v3: - removed TODOs from comments Change-Id: I684d23dac5a22eb0a4cea71993cb934302b17cea --- arch/x86/entry/common.c | 1 + arch/x86/include/asm/irq_regs.h | 1 + arch/x86/include/asm/syscall_wrapper.h | 1 + arch/x86/kernel/apic/apic.c | 1 + arch/x86/kernel/dumpstack_64.c | 1 + arch/x86/kernel/process_64.c | 5 +++++ arch/x86/kernel/traps.c | 12 ++++++++++-- arch/x86/kernel/uprobes.c | 7 ++++++- kernel/profile.c | 1 + kernel/sched/core.c | 6 ++++++ 10 files changed, 33 insertions(+), 3 deletions(-)