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Date: Tue, 19 Nov 2019 15:51:52 -0600
From: Tianlin Li <tli@...italocean.com>
To: Kees Cook <keescook@...omium.org>
Cc: kernel-hardening@...ts.openwall.com,
Steven Rostedt <rostedt@...dmis.org>,
Ingo Molnar <mingo@...hat.com>,
Russell King <linux@...linux.org.uk>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Greentime Hu <green.hu@...il.com>,
Vincent Chen <deanbo422@...il.com>,
Thomas Gleixner <tglx@...utronix.de>,
Borislav Petkov <bp@...en8.de>,
"H . Peter Anvin" <hpa@...or.com>,
x86@...nel.org,
Jessica Yu <jeyu@...nel.org>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Jiri Kosina <jikos@...nel.org>,
Miroslav Benes <mbenes@...e.cz>,
Petr Mladek <pmladek@...e.com>,
Joe Lawrence <joe.lawrence@...hat.com>
Subject: Re: [RFC PATCH] kernel/module: have the callers of set_memory_*()
check the return value
> On Nov 19, 2019, at 11:07 AM, Kees Cook <keescook@...omium.org> wrote:
>
> On Tue, Nov 19, 2019 at 09:51:49AM -0600, Tianlin Li wrote:
>> Right now several architectures allow their set_memory_*() family of
>> functions to fail, but callers may not be checking the return values. We
>> need to fix the callers and add the __must_check attribute. They also may
>> not provide any level of atomicity, in the sense that the memory
>> protections may be left incomplete on failure. This issue likely has a few
>> steps on effects architectures[1]:
>
> Awesome; thanks for working on this!
>
> A few suggestions on this patch, which will help reviewers, below...
>
>> 1)Have all callers of set_memory_*() helpers check the return value.
>> 2)Add __much_check to all set_memory_*() helpers so that new uses do not
>> ignore the return value.
>> 3)Add atomicity to the calls so that the memory protections aren't left in
>> a partial state.
>
> Maybe clarify to say something like "this series is step 1”?
ok. Will add the clarification. Thanks!
>
>>
>> Ideally, the failure of set_memory_*() should be passed up the call stack,
>> and callers should examine the failure and deal with it. But currently,
>> some callers just have void return type.
>>
>> We need to fix the callers to handle the return all the way to the top of
>> stack, and it will require a large series of patches to finish all the three
>> steps mentioned above. I start with kernel/module, and will move onto other
>> subsystems. I am not entirely sure about the failure modes for each caller.
>> So I would like to get some comments before I move forward. This single
>> patch is just for fixing the return value of set_memory_*() function in
>> kernel/module, and also the related callers. Any feedback would be greatly
>> appreciated.
>>
>> [1]:https://github.com/KSPP/linux/issues/7
>>
>> Signed-off-by: Tianlin Li <tli@...italocean.com>
>> ---
>> arch/arm/kernel/ftrace.c | 8 +-
>> arch/arm64/kernel/ftrace.c | 6 +-
>> arch/nds32/kernel/ftrace.c | 6 +-
>> arch/x86/kernel/ftrace.c | 13 ++-
>> include/linux/module.h | 16 ++--
>> kernel/livepatch/core.c | 15 +++-
>> kernel/module.c | 170 +++++++++++++++++++++++++++----------
>> kernel/trace/ftrace.c | 15 +++-
>> 8 files changed, 175 insertions(+), 74 deletions(-)
>
> - Can you break this patch into 3 separate patches, by "subsystem":
> - ftrace
> - module
> - livepatch (unless Jessica thinks maybe livepatch should go
> with module?)
> - Please run patches through scripts/checkpatch.pl to catch common
> coding style issues (e.g. blank line between variable declarations
> and function body).
> - These changes look pretty straight forward, so I think it'd be fine
> to drop the "RFC" tag and include linux-kernel@...r.kernel.org <mailto:linux-kernel@...r.kernel.org> in the
> Cc list for the v2. For lots of detail, see:
> https://www.kernel.org/doc/html/latest/process/submitting-patches.html <https://www.kernel.org/doc/html/latest/process/submitting-patches.html>
ok. I will fix them in v2. Thanks a lot!
> More below...
>
>>
>> diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
>> index bda949fd84e8..7ea1338821d6 100644
>> --- a/arch/arm/kernel/ftrace.c
>> +++ b/arch/arm/kernel/ftrace.c
>> @@ -59,13 +59,15 @@ static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
>>
>> int ftrace_arch_code_modify_prepare(void)
>> {
>> - set_all_modules_text_rw();
>> - return 0;
>> + return set_all_modules_text_rw();
>> }
>>
>> int ftrace_arch_code_modify_post_process(void)
>> {
>> - set_all_modules_text_ro();
>> + int ret;
>
> Blank line here...
>
>> + ret = set_all_modules_text_ro();
>> + if (ret)
>> + return ret;
>> /* Make sure any TLB misses during machine stop are cleared. */
>> flush_tlb_all();
>> return 0;
>
> Are callers of these ftrace functions checking return values too?
ftrace_arch_code_modify_prepare is called in ftrace_run_update_code and ftrace_module_enable.
ftrace_run_update_code is checking the return value of ftrace_arch_code_modify_prepare already.
ftrace_module_enable didn’t check. (I modifies this function in this patch to check the return value of ftrace_arch_code_modify_prepare ).
Same for ftrace_arch_code_modify_post_process.
>> diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
>> index 171773257974..97a89c38f6b9 100644
>> --- a/arch/arm64/kernel/ftrace.c
>> +++ b/arch/arm64/kernel/ftrace.c
>> @@ -115,9 +115,11 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
>> }
>>
>> /* point the trampoline to our ftrace entry point */
>> - module_disable_ro(mod);
>> + if (module_disable_ro(mod))
>> + return -EINVAL;
>> *dst = trampoline;
>> - module_enable_ro(mod, true);
>> + if (module_enable_ro(mod, true))
>> + return -EINVAL;
>>
>> /*
>> * Ensure updated trampoline is visible to instruction
>> diff --git a/arch/nds32/kernel/ftrace.c b/arch/nds32/kernel/ftrace.c
>> index fd2a54b8cd57..e9e63e703a3e 100644
>> --- a/arch/nds32/kernel/ftrace.c
>> +++ b/arch/nds32/kernel/ftrace.c
>> @@ -91,14 +91,12 @@ int __init ftrace_dyn_arch_init(void)
>>
>> int ftrace_arch_code_modify_prepare(void)
>> {
>> - set_all_modules_text_rw();
>> - return 0;
>> + return set_all_modules_text_rw();
>> }
>>
>> int ftrace_arch_code_modify_post_process(void)
>> {
>> - set_all_modules_text_ro();
>> - return 0;
>> + return set_all_modules_text_ro();
>> }
>>
>> static unsigned long gen_sethi_insn(unsigned long addr)
>> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
>> index 024c3053dbba..7fdee06e2a76 100644
>> --- a/arch/x86/kernel/ftrace.c
>> +++ b/arch/x86/kernel/ftrace.c
>> @@ -42,19 +42,26 @@ int ftrace_arch_code_modify_prepare(void)
>> * and live kernel patching from changing the text permissions while
>> * ftrace has it set to "read/write".
>> */
>> + int ret;
>> mutex_lock(&text_mutex);
>> set_kernel_text_rw();
>> - set_all_modules_text_rw();
>> + ret = set_all_modules_text_rw();
>> + if (ret) {
>> + set_kernel_text_ro();
>
> Is the set_kernel_text_ro() here is an atomicity fix? Also, won't a future
> patch need to check the result of that function call? (i.e. should it
> be left out of this series and should atomicity fixes happen inside the
> set_memory_*() functions? Can they happen there?)
set_kernel_text_tro() here was not for an atomicity fix in step 3, it was just for reverting the status
in ftrace_arch_code_modify_prepare, because set_kernel_text_rw() is called.
Thanks for pointing it out. I will check it.
>
>> + mutex_unlock(&text_mutex);
>> + return ret;
>> + }
>> return 0;
>> }
>>
>> int ftrace_arch_code_modify_post_process(void)
>> __releases(&text_mutex)
>> {
>> - set_all_modules_text_ro();
>> + int ret;
>
> blank line needed...
>
>> + ret = set_all_modules_text_ro();
>> set_kernel_text_ro();
>> mutex_unlock(&text_mutex);
>> - return 0;
>> + return ret;
>> }
>>
>> union ftrace_code_union {
>> diff --git a/include/linux/module.h b/include/linux/module.h
>> index 1455812dd325..e6c7f3b719a3 100644
>> --- a/include/linux/module.h
>> +++ b/include/linux/module.h
>> @@ -847,15 +847,15 @@ extern int module_sysfs_initialized;
>> #define __MODULE_STRING(x) __stringify(x)
>>
>> #ifdef CONFIG_STRICT_MODULE_RWX
>> -extern void set_all_modules_text_rw(void);
>> -extern void set_all_modules_text_ro(void);
>> -extern void module_enable_ro(const struct module *mod, bool after_init);
>> -extern void module_disable_ro(const struct module *mod);
>> +extern int set_all_modules_text_rw(void);
>> +extern int set_all_modules_text_ro(void);
>> +extern int module_enable_ro(const struct module *mod, bool after_init);
>> +extern int module_disable_ro(const struct module *mod);
>> #else
>> -static inline void set_all_modules_text_rw(void) { }
>> -static inline void set_all_modules_text_ro(void) { }
>> -static inline void module_enable_ro(const struct module *mod, bool after_init) { }
>> -static inline void module_disable_ro(const struct module *mod) { }
>> +static inline int set_all_modules_text_rw(void) { return 0; }
>> +static inline int set_all_modules_text_ro(void) { return 0; }
>> +static inline int module_enable_ro(const struct module *mod, bool after_init) { return 0; }
>
> Please wrap this line (yes, the old one wasn't...)
>
>> +static inline int module_disable_ro(const struct module *mod) { return 0; }
>> #endif
>>
>> #ifdef CONFIG_GENERIC_BUG
>> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
>> index c4ce08f43bd6..39bfc0685854 100644
>> --- a/kernel/livepatch/core.c
>> +++ b/kernel/livepatch/core.c
>> @@ -721,16 +721,25 @@ static int klp_init_object_loaded(struct klp_patch *patch,
>>
>> mutex_lock(&text_mutex);
>>
>> - module_disable_ro(patch->mod);
>> + ret = module_disable_ro(patch->mod);
>> + if (ret) {
>> + mutex_unlock(&text_mutex);
>> + return ret;
>> + }
>> ret = klp_write_object_relocations(patch->mod, obj);
>> if (ret) {
>> - module_enable_ro(patch->mod, true);
>> + if (module_enable_ro(patch->mod, true));
>> + pr_err("module_enable_ro failed.\n");
>
> Why the pr_err() here and not in other failure cases? (Also, should it
> instead be a WARN_ONCE() inside the set_memory_*() functions instead?)
Because module_enable_ro() is called in the checking of another return value. I can not return the value, so I print the error.
Similar to the previous question, should it be fixed by atomicity patches later?
>
>> mutex_unlock(&text_mutex);
>> return ret;
>> }
>>
>> arch_klp_init_object_loaded(patch, obj);
>> - module_enable_ro(patch->mod, true);
>> + ret = module_enable_ro(patch->mod, true);
>> + if (ret) {
>> + mutex_unlock(&text_mutex);
>> + return ret;
>> + }
>>
>> mutex_unlock(&text_mutex);
>>
>> diff --git a/kernel/module.c b/kernel/module.c
>> index 9ee93421269c..87125b5e315c 100644
>> --- a/kernel/module.c
>> +++ b/kernel/module.c
>> @@ -1900,111 +1900,162 @@ static void mod_sysfs_teardown(struct module *mod)
>> *
>> * These values are always page-aligned (as is base)
>> */
>> -static void frob_text(const struct module_layout *layout,
>> +static int frob_text(const struct module_layout *layout,
>> int (*set_memory)(unsigned long start, int num_pages))
>> {
>> BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1));
>> BUG_ON((unsigned long)layout->text_size & (PAGE_SIZE-1));
>> - set_memory((unsigned long)layout->base,
>> + return set_memory((unsigned long)layout->base,
>> layout->text_size >> PAGE_SHIFT);
>> }
>>
>> #ifdef CONFIG_STRICT_MODULE_RWX
>> -static void frob_rodata(const struct module_layout *layout,
>> +static int frob_rodata(const struct module_layout *layout,
>> int (*set_memory)(unsigned long start, int num_pages))
>> {
>> BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1));
>> BUG_ON((unsigned long)layout->text_size & (PAGE_SIZE-1));
>> BUG_ON((unsigned long)layout->ro_size & (PAGE_SIZE-1));
>> - set_memory((unsigned long)layout->base + layout->text_size,
>> + return set_memory((unsigned long)layout->base + layout->text_size,
>> (layout->ro_size - layout->text_size) >> PAGE_SHIFT);
>> }
>>
>> -static void frob_ro_after_init(const struct module_layout *layout,
>> +static int frob_ro_after_init(const struct module_layout *layout,
>> int (*set_memory)(unsigned long start, int num_pages))
>> {
>> BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1));
>> BUG_ON((unsigned long)layout->ro_size & (PAGE_SIZE-1));
>> BUG_ON((unsigned long)layout->ro_after_init_size & (PAGE_SIZE-1));
>> - set_memory((unsigned long)layout->base + layout->ro_size,
>> + return set_memory((unsigned long)layout->base + layout->ro_size,
>> (layout->ro_after_init_size - layout->ro_size) >> PAGE_SHIFT);
>> }
>>
>> -static void frob_writable_data(const struct module_layout *layout,
>> +static int frob_writable_data(const struct module_layout *layout,
>> int (*set_memory)(unsigned long start, int num_pages))
>> {
>> BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1));
>> BUG_ON((unsigned long)layout->ro_after_init_size & (PAGE_SIZE-1));
>> BUG_ON((unsigned long)layout->size & (PAGE_SIZE-1));
>> - set_memory((unsigned long)layout->base + layout->ro_after_init_size,
>> + return set_memory((unsigned long)layout->base + layout->ro_after_init_size,
>> (layout->size - layout->ro_after_init_size) >> PAGE_SHIFT);
>> }
>>
>> /* livepatching wants to disable read-only so it can frob module. */
>> -void module_disable_ro(const struct module *mod)
>> +int module_disable_ro(const struct module *mod)
>> {
>> + int ret;
>> if (!rodata_enabled)
>> - return;
>> + return 0;
>>
>> - frob_text(&mod->core_layout, set_memory_rw);
>> - frob_rodata(&mod->core_layout, set_memory_rw);
>> - frob_ro_after_init(&mod->core_layout, set_memory_rw);
>> - frob_text(&mod->init_layout, set_memory_rw);
>> - frob_rodata(&mod->init_layout, set_memory_rw);
>> + ret = frob_text(&mod->core_layout, set_memory_rw);
>> + if (ret)
>> + return ret;
>> + ret = frob_rodata(&mod->core_layout, set_memory_rw);
>> + if (ret)
>> + return ret;
>> + ret = frob_ro_after_init(&mod->core_layout, set_memory_rw);
>> + if (ret)
>> + return ret;
>> + ret = frob_text(&mod->init_layout, set_memory_rw);
>> + if (ret)
>> + return ret;
>> + ret = frob_rodata(&mod->init_layout, set_memory_rw);
>> + if (ret)
>> + return ret;
>> +
>> + return 0;
>> }
>>
>> -void module_enable_ro(const struct module *mod, bool after_init)
>> +int module_enable_ro(const struct module *mod, bool after_init)
>> {
>> + int ret;
>> if (!rodata_enabled)
>> - return;
>> + return 0;
>>
>> set_vm_flush_reset_perms(mod->core_layout.base);
>> set_vm_flush_reset_perms(mod->init_layout.base);
>> - frob_text(&mod->core_layout, set_memory_ro);
>> + ret = frob_text(&mod->core_layout, set_memory_ro);
>> + if (ret)
>> + return ret;
>>
>> - frob_rodata(&mod->core_layout, set_memory_ro);
>> - frob_text(&mod->init_layout, set_memory_ro);
>> - frob_rodata(&mod->init_layout, set_memory_ro);
>> + ret = frob_rodata(&mod->core_layout, set_memory_ro);
>> + if (ret)
>> + return ret;
>> + ret = frob_text(&mod->init_layout, set_memory_ro);
>> + if (ret)
>> + return ret;
>> + ret = frob_rodata(&mod->init_layout, set_memory_ro);
>> + if (ret)
>> + return ret;
>>
>> - if (after_init)
>> - frob_ro_after_init(&mod->core_layout, set_memory_ro);
>> + if (after_init) {
>> + ret = frob_ro_after_init(&mod->core_layout, set_memory_ro);
>> + if (ret)
>> + return ret;
>> + }
>> + return 0;
>> }
>>
>> -static void module_enable_nx(const struct module *mod)
>> +static int module_enable_nx(const struct module *mod)
>> {
>> - frob_rodata(&mod->core_layout, set_memory_nx);
>> - frob_ro_after_init(&mod->core_layout, set_memory_nx);
>> - frob_writable_data(&mod->core_layout, set_memory_nx);
>> - frob_rodata(&mod->init_layout, set_memory_nx);
>> - frob_writable_data(&mod->init_layout, set_memory_nx);
>> + int ret;
>> +
>> + ret = frob_rodata(&mod->core_layout, set_memory_nx);
>> + if (ret)
>> + return ret;
>> + ret = frob_ro_after_init(&mod->core_layout, set_memory_nx);
>> + if (ret)
>> + return ret;
>> + ret = frob_writable_data(&mod->core_layout, set_memory_nx);
>> + if (ret)
>> + return ret;
>> + ret = frob_rodata(&mod->init_layout, set_memory_nx);
>> + if (ret)
>> + return ret;
>> + ret = frob_writable_data(&mod->init_layout, set_memory_nx);
>> + if (ret)
>> + return ret;
>> +
>> + return 0;
>> }
>>
>> /* Iterate through all modules and set each module's text as RW */
>> -void set_all_modules_text_rw(void)
>> +int set_all_modules_text_rw(void)
>> {
>> struct module *mod;
>> + int ret;
>>
>> if (!rodata_enabled)
>> - return;
>> + return 0;
>>
>> mutex_lock(&module_mutex);
>> list_for_each_entry_rcu(mod, &modules, list) {
>> if (mod->state == MODULE_STATE_UNFORMED)
>> continue;
>>
>> - frob_text(&mod->core_layout, set_memory_rw);
>> - frob_text(&mod->init_layout, set_memory_rw);
>> + ret = frob_text(&mod->core_layout, set_memory_rw);
>> + if (ret) {
>> + mutex_unlock(&module_mutex);
>> + return ret;
>> + }
>> + ret = frob_text(&mod->init_layout, set_memory_rw);
>> + if (ret) {
>> + mutex_unlock(&module_mutex);
>> + return ret;
>> + }
>
> This pattern feels like it might be better with a "goto out" style:
>
> mutex_lock...
> list_for_each... {
> ret = frob_...
> if (ret)
> goto out;
> ret = frob_...
> if (ret)
> goto out;
> }
> ret = 0;
> out:
> mutex_unlock...
> return ret;
Thanks! Will fix it in v2.
>
>> }
>> mutex_unlock(&module_mutex);
>> + return 0;
>> }
>>
>> /* Iterate through all modules and set each module's text as RO */
>> -void set_all_modules_text_ro(void)
>> +int set_all_modules_text_ro(void)
>> {
>> struct module *mod;
>> + int ret;
>>
>> if (!rodata_enabled)
>> - return;
>> + return 0;
>>
>> mutex_lock(&module_mutex);
>> list_for_each_entry_rcu(mod, &modules, list) {
>> @@ -2017,22 +2068,37 @@ void set_all_modules_text_ro(void)
>> mod->state == MODULE_STATE_GOING)
>> continue;
>>
>> - frob_text(&mod->core_layout, set_memory_ro);
>> - frob_text(&mod->init_layout, set_memory_ro);
>> + ret = frob_text(&mod->core_layout, set_memory_ro);
>> + if (ret) {
>> + mutex_unlock(&module_mutex);
>> + return ret;
>> + }
>> + ret = frob_text(&mod->init_layout, set_memory_ro);
>> + if (ret) {
>> + mutex_unlock(&module_mutex);
>> + return ret;
>> + }
>> }
>> mutex_unlock(&module_mutex);
>> + return 0;
>> }
>> #else /* !CONFIG_STRICT_MODULE_RWX */
>> -static void module_enable_nx(const struct module *mod) { }
>> +static int module_enable_nx(const struct module *mod) { return 0; }
>> #endif /* CONFIG_STRICT_MODULE_RWX */
>> -static void module_enable_x(const struct module *mod)
>> +static int module_enable_x(const struct module *mod)
>> {
>> - frob_text(&mod->core_layout, set_memory_x);
>> - frob_text(&mod->init_layout, set_memory_x);
>> + int ret;
>> + ret = frob_text(&mod->core_layout, set_memory_x);
>> + if (ret)
>> + return ret;
>> + ret = frob_text(&mod->init_layout, set_memory_x);
>> + if (ret)
>> + return ret;
>> + return 0;
>> }
>> #else /* !CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
>> -static void module_enable_nx(const struct module *mod) { }
>> -static void module_enable_x(const struct module *mod) { }
>> +static int module_enable_nx(const struct module *mod) { return 0; }
>> +static int module_enable_x(const struct module *mod) { return 0; }
>> #endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
>>
>>
>> @@ -3534,7 +3600,11 @@ static noinline int do_init_module(struct module *mod)
>> /* Switch to core kallsyms now init is done: kallsyms may be walking! */
>> rcu_assign_pointer(mod->kallsyms, &mod->core_kallsyms);
>> #endif
>> - module_enable_ro(mod, true);
>> + ret = module_enable_ro(mod, true);
>> + if (ret) {
>> + mutex_unlock(&module_mutex);
>> + goto fail_free_freeinit;
>> + }
>> mod_tree_remove_init(mod);
>> module_arch_freeing_init(mod);
>> mod->init_layout.base = NULL;
>> @@ -3640,9 +3710,15 @@ static int complete_formation(struct module *mod, struct load_info *info)
>> /* This relies on module_mutex for list integrity. */
>> module_bug_finalize(info->hdr, info->sechdrs, mod);
>>
>> - module_enable_ro(mod, false);
>> - module_enable_nx(mod);
>> - module_enable_x(mod);
>> + err = module_enable_ro(mod, false);
>> + if (err)
>> + goto out;
>> + err = module_enable_nx(mod);
>> + if (err)
>> + goto out;
>> + err = module_enable_x(mod);
>> + if (err)
>> + goto out;
>>
>> /* Mark state as coming so strong_try_module_get() ignores us,
>> * but kallsyms etc. can see us. */
>> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
>> index f9821a3374e9..d4532bb65d1b 100644
>> --- a/kernel/trace/ftrace.c
>> +++ b/kernel/trace/ftrace.c
>> @@ -5814,8 +5814,13 @@ void ftrace_module_enable(struct module *mod)
>> * text to read-only, as we now need to set it back to read-write
>> * so that we can modify the text.
>> */
>> - if (ftrace_start_up)
>> - ftrace_arch_code_modify_prepare();
>> + if (ftrace_start_up) {
>> + int ret = ftrace_arch_code_modify_prepare();
>> + if (ret) {
>> + FTRACE_WARN_ON(ret);
>> + goto out_unlock;
>> + }
>
> Can FTRACE_WARN_ON() be used in an "if" like WARN_ON? This could maybe
> look like:
>
> ret = ftrace_arch...
> if (FTRACE_WARN_ON(ret))
> goto out_unlock
>
> Though I not this doesn't result in an error getting passed up? i.e.
> ftrace_module_enable() is still "void". Does that matter here?
Thanks. I will fix it in v2.
>> + }
>>
>> do_for_each_ftrace_rec(pg, rec) {
>> int cnt;
>> @@ -5854,8 +5859,10 @@ void ftrace_module_enable(struct module *mod)
>> } while_for_each_ftrace_rec();
>>
>> out_loop:
>> - if (ftrace_start_up)
>> - ftrace_arch_code_modify_post_process();
>> + if (ftrace_start_up) {
>> + int ret = ftrace_arch_code_modify_post_process();
>> + FTRACE_WARN_ON(ret);
>> + }
>>
>> out_unlock:
>> mutex_unlock(&ftrace_lock);
>> --
>> 2.17.1
>>
>
> Thanks,
Thanks for all detail suggestions!
> --
> Kees Cook
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