Messages in this thread Patch in this message | | | Date | Sat, 13 Oct 2018 14:34:23 -0400 (EDT) | From | Mathieu Desnoyers <> | Subject | Re: [PATCH for 4.19] tracepoint: Fix: out-of-bound tracepoint array iteration |
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----- On Oct 13, 2018, at 11:24 AM, Ard Biesheuvel ard.biesheuvel@linaro.org wrote:
> On 12 October 2018 at 23:07, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: >> Hi Mathieu, >> >> On 12 October 2018 at 22:05, Mathieu Desnoyers >> <mathieu.desnoyers@efficios.com> wrote: >>> commit 46e0c9be206f ("kernel: tracepoints: add support for relative >>> references") changes the layout of the __tracepoint_ptrs section on >>> architectures supporting relative references. However, it does so >>> without turning struct tracepoint * const into const int * elsewhere in >>> the tracepoint code, which has the following side-effect: >>> >>> tracepoint_module_{coming,going} invoke >>> tp_module_going_check_quiescent() with mod->tracepoints_ptrs >>> as first argument, and computes the end address of the array >>> for the second argument with: >>> >>> mod->tracepoints_ptrs + mod->num_tracepoints >>> >>> However, because the type of mod->tracepoint_ptrs in module.h >>> has not been changed from pointer to int, it passes an end >>> pointer which is twice larger than the array, causing out-of-bound >>> array accesses. >>> >>> Fix this by introducing a new typedef: tracepoint_ptr_t, which >>> is either "const int" on architectures that have PREL32 relocations, >>> or "struct tracepoint * const" on architectures that does not have >>> this feature. >>> >>> Also provide a new tracepoint_ptr_defer() static inline to >>> encapsulate deferencing this type rather than duplicate code and >>> ugly idefs within the for_each_tracepoint_range() implementation. >>> >> >> Apologies for the breakage. FWIW, this looks like the correct approach >> to me (and mirrors what I did for initcalls in the same series) >> >>> This issue appears in 4.19-rc kernels, and should ideally be fixed >>> before the end of the rc cycle. >>> >> >> +1 >> >>> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> >>> Link: http://lkml.kernel.org/r/20180704083651.24360-7-ard.biesheuvel@linaro.org >>> Cc: Michael Ellerman <mpe@ellerman.id.au> >>> Cc: Ingo Molnar <mingo@kernel.org> >>> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> >>> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> >>> Cc: Arnd Bergmann <arnd@arndb.de> >>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> >>> Cc: Bjorn Helgaas <bhelgaas@google.com> >>> Cc: Catalin Marinas <catalin.marinas@arm.com> >>> Cc: James Morris <james.morris@microsoft.com> >>> Cc: James Morris <jmorris@namei.org> >>> Cc: Jessica Yu <jeyu@kernel.org> >>> Cc: Josh Poimboeuf <jpoimboe@redhat.com> >>> Cc: Kees Cook <keescook@chromium.org> >>> Cc: Nicolas Pitre <nico@linaro.org> >>> Cc: Paul Mackerras <paulus@samba.org> >>> Cc: Petr Mladek <pmladek@suse.com> >>> Cc: Russell King <linux@armlinux.org.uk> >>> Cc: "Serge E. Hallyn" <serge@hallyn.com> >>> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> >>> Cc: Thomas Garnier <thgarnie@google.com> >>> Cc: Thomas Gleixner <tglx@linutronix.de> >>> Cc: Will Deacon <will.deacon@arm.com> >>> Cc: Andrew Morton <akpm@linux-foundation.org> >>> Cc: Linus Torvalds <torvalds@linux-foundation.org> >>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >> >> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> >> > > This fixes the build breakage for me that kbuild test robot reports. > > diff --git a/include/linux/module.h b/include/linux/module.h > index cdab2451d6be..e19ae08c7fb8 100644 > --- a/include/linux/module.h > +++ b/include/linux/module.h > @@ -20,6 +20,7 @@ > #include <linux/export.h> > #include <linux/rbtree_latch.h> > #include <linux/error-injection.h> > +#include <linux/tracepoint-defs.h>
You've beat me to it :) I'll fold this change in a v2 of the patch,
Thanks!
Mathieu
> > #include <linux/percpu.h> > #include <asm/module.h> > > > > > >>> --- >>> include/linux/module.h | 2 +- >>> include/linux/tracepoint-defs.h | 6 ++++++ >>> include/linux/tracepoint.h | 36 +++++++++++++++++++++------------ >>> kernel/tracepoint.c | 24 ++++++++-------------- >>> 4 files changed, 38 insertions(+), 30 deletions(-) >>> >>> diff --git a/include/linux/module.h b/include/linux/module.h >>> index f807f15bebbe..cdab2451d6be 100644 >>> --- a/include/linux/module.h >>> +++ b/include/linux/module.h >>> @@ -430,7 +430,7 @@ struct module { >>> >>> #ifdef CONFIG_TRACEPOINTS >>> unsigned int num_tracepoints; >>> - struct tracepoint * const *tracepoints_ptrs; >>> + tracepoint_ptr_t *tracepoints_ptrs; >>> #endif >>> #ifdef HAVE_JUMP_LABEL >>> struct jump_entry *jump_entries; >>> diff --git a/include/linux/tracepoint-defs.h b/include/linux/tracepoint-defs.h >>> index 22c5a46e9693..49ba9cde7e4b 100644 >>> --- a/include/linux/tracepoint-defs.h >>> +++ b/include/linux/tracepoint-defs.h >>> @@ -35,6 +35,12 @@ struct tracepoint { >>> struct tracepoint_func __rcu *funcs; >>> }; >>> >>> +#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS >>> +typedef const int tracepoint_ptr_t; >>> +#else >>> +typedef struct tracepoint * const tracepoint_ptr_t; >>> +#endif >>> + >>> struct bpf_raw_event_map { >>> struct tracepoint *tp; >>> void *bpf_func; >>> diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h >>> index 041f7e56a289..538ba1a58f5b 100644 >>> --- a/include/linux/tracepoint.h >>> +++ b/include/linux/tracepoint.h >>> @@ -99,6 +99,29 @@ extern void syscall_unregfunc(void); >>> #define TRACE_DEFINE_ENUM(x) >>> #define TRACE_DEFINE_SIZEOF(x) >>> >>> +#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS >>> +static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) >>> +{ >>> + return offset_to_ptr(p); >>> +} >>> + >>> +#define __TRACEPOINT_ENTRY(name) \ >>> + asm(" .section \"__tracepoints_ptrs\", \"a\" \n" \ >>> + " .balign 4 \n" \ >>> + " .long __tracepoint_" #name " - . \n" \ >>> + " .previous \n") >>> +#else >>> +static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) >>> +{ >>> + return *p; >>> +} >>> + >>> +#define __TRACEPOINT_ENTRY(name) \ >>> + static tracepoint_ptr_t __tracepoint_ptr_##name __used \ >>> + __attribute__((section("__tracepoints_ptrs"))) = \ >>> + &__tracepoint_##name >>> +#endif >>> + >>> #endif /* _LINUX_TRACEPOINT_H */ >>> >>> /* >>> @@ -253,19 +276,6 @@ extern void syscall_unregfunc(void); >>> return static_key_false(&__tracepoint_##name.key); \ >>> } >>> >>> -#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS >>> -#define __TRACEPOINT_ENTRY(name) \ >>> - asm(" .section \"__tracepoints_ptrs\", \"a\" \n" \ >>> - " .balign 4 \n" \ >>> - " .long __tracepoint_" #name " - . \n" \ >>> - " .previous \n") >>> -#else >>> -#define __TRACEPOINT_ENTRY(name) \ >>> - static struct tracepoint * const __tracepoint_ptr_##name __used \ >>> - __attribute__((section("__tracepoints_ptrs"))) = \ >>> - &__tracepoint_##name >>> -#endif >>> - >>> /* >>> * We have no guarantee that gcc and the linker won't up-align the tracepoint >>> * structures, so we create an array of pointers that will be used for iteration >>> diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c >>> index bf2c06ef9afc..a3be42304485 100644 >>> --- a/kernel/tracepoint.c >>> +++ b/kernel/tracepoint.c >>> @@ -28,8 +28,8 @@ >>> #include <linux/sched/task.h> >>> #include <linux/static_key.h> >>> >>> -extern struct tracepoint * const __start___tracepoints_ptrs[]; >>> -extern struct tracepoint * const __stop___tracepoints_ptrs[]; >>> +extern tracepoint_ptr_t __start___tracepoints_ptrs[]; >>> +extern tracepoint_ptr_t __stop___tracepoints_ptrs[]; >>> >>> DEFINE_SRCU(tracepoint_srcu); >>> EXPORT_SYMBOL_GPL(tracepoint_srcu); >>> @@ -371,25 +371,17 @@ int tracepoint_probe_unregister(struct tracepoint *tp, >>> void *probe, void *data) >>> } >>> EXPORT_SYMBOL_GPL(tracepoint_probe_unregister); >>> >>> -static void for_each_tracepoint_range(struct tracepoint * const *begin, >>> - struct tracepoint * const *end, >>> +static void for_each_tracepoint_range( >>> + tracepoint_ptr_t *begin, tracepoint_ptr_t *end, >>> void (*fct)(struct tracepoint *tp, void *priv), >>> void *priv) >>> { >>> + tracepoint_ptr_t *iter; >>> + >>> if (!begin) >>> return; >>> - >>> - if (IS_ENABLED(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS)) { >>> - const int *iter; >>> - >>> - for (iter = (const int *)begin; iter < (const int *)end; iter++) >>> - fct(offset_to_ptr(iter), priv); >>> - } else { >>> - struct tracepoint * const *iter; >>> - >>> - for (iter = begin; iter < end; iter++) >>> - fct(*iter, priv); >>> - } >>> + for (iter = begin; iter < end; iter++) >>> + fct(tracepoint_ptr_deref(iter), priv); >>> } >>> >>> #ifdef CONFIG_MODULES >>> -- >>> 2.17.1
-- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
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