| From | Arnd Bergmann <> | Date | Wed, 27 Apr 2022 09:14:48 +0200 | Subject | Re: [PATCH v3 05/46] x86: asm: instrument usercopy in get_user() and __put_user_size() |
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On Tue, Apr 26, 2022 at 6:42 PM Alexander Potapenko <glider@google.com> wrote: > @@ -99,11 +100,13 @@ extern int __get_user_bad(void); > int __ret_gu; \ > register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \ > __chk_user_ptr(ptr); \ > + instrument_copy_from_user_before((void *)&(x), ptr, sizeof(*(ptr))); \ > asm volatile("call __" #fn "_%P4" \ > : "=a" (__ret_gu), "=r" (__val_gu), \ > ASM_CALL_CONSTRAINT \ > : "0" (ptr), "i" (sizeof(*(ptr)))); \ > (x) = (__force __typeof__(*(ptr))) __val_gu; \ > + instrument_copy_from_user_after((void *)&(x), ptr, sizeof(*(ptr)), 0); \
Isn't "ptr" the original pointer here? I think what happened with the reported warning is that you get one output line for every instance this is used in. There should probably be a
__auto_type __ptr = (ptr);
at the beginning of the macro to ensure that 'ptr' is only evaluated once.
>>> arch/x86/kernel/signal.c:360:9: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected void [noderef] __user *to @@ got unsigned long long [usertype] * @@
It would also make sense to add the missing __user annotation in this line, but I suspect there are others like it in drivers.
Arnd
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