Messages in this thread Patch in this message | | | Date | Mon, 15 Oct 2018 13:34:33 +0200 | From | Jessica Yu <> | Subject | Re: [PATCH for 4.19] tracepoint: Fix: out-of-bound tracepoint array iteration |
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+++ Mathieu Desnoyers [12/10/18 16:05 -0400]: >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. > >This issue appears in 4.19-rc kernels, and should ideally be fixed >before the end of the rc cycle. > >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>
For module parts:
Acked-by: Jessica Yu <jeyu@kernel.org>
>--- > 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 >
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