On Tue, Apr 26, 2022 at 6:42 PM Alexander Potapenko <[email protected]> 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
On Wed, Apr 27, 2022 at 9:15 AM Arnd Bergmann <[email protected]> wrote:
>
> On Tue, Apr 26, 2022 at 6:42 PM Alexander Potapenko <[email protected]> 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
I ran sparse locally, and it is actually the missing __user
annotations in signal.c that cause these reports.
The following patch:
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index e439eb14325fa..68537dbffa545 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -355,7 +355,7 @@ __setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
* reasons and because gdb uses it as a signature to notice
* signal handler stack frames.
*/
- unsafe_put_user(*((u64 *)&retcode), (u64 *)frame->retcode, Efault);
+ unsafe_put_user(*((u64 *)&retcode), (__user u64
*)frame->retcode, Efault);
user_access_end();
/* Set up registers for signal handler */
@@ -415,7 +415,7 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig,
* reasons and because gdb uses it as a signature to notice
* signal handler stack frames.
*/
- unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault);
+ unsafe_put_user(*((u64 *)&rt_retcode), (__user u64
*)frame->retcode, Efault);
unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
unsafe_put_sigmask(set, frame, Efault);
user_access_end();
appears to fix sparse warnings.
--
Alexander Potapenko
Software Engineer
Google Germany GmbH
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