If the get_user(x, ptr) has x as a pointer, then the setting
of (x) = 0 is going to produce the following sparse warning,
so fix this by forcing the type of 'x' when access_ok() fails.

fs/aio.c:2073:21: warning: Using plain integer as NULL pointer

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
---
 arch/riscv/include/asm/uaccess.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
index 855450bed9f5..ec0cab9fbddd 100644
--- a/arch/riscv/include/asm/uaccess.h
+++ b/arch/riscv/include/asm/uaccess.h
@@ -165,7 +165,7 @@ do {								\
 	might_fault();						\
 	access_ok(__p, sizeof(*__p)) ?		\
 		__get_user((x), __p) :				\
-		((x) = 0, -EFAULT);				\
+		((x) = (__force __typeof__(x))0, -EFAULT);	\
 })
 
 #define __put_user_asm(insn, x, ptr, err)			\
-- 
2.39.0

Hello:

This patch was applied to riscv/linux.git (fixes)
by Palmer Dabbelt <palmer@rivosinc.com>:

On Thu, 29 Dec 2022 17:05:45 +0000 you wrote:
> If the get_user(x, ptr) has x as a pointer, then the setting
> of (x) = 0 is going to produce the following sparse warning,
> so fix this by forcing the type of 'x' when access_ok() fails.
> 
> fs/aio.c:2073:21: warning: Using plain integer as NULL pointer
> 
> Signed-off-by: Ben Dooks <ben-linux@fluff.org>
> 
> [...]

Here is the summary with links:
  - riscv: uaccess: fix type of 0 variable on error in get_user()
    https://git.kernel.org/riscv/c/b9b916aee671

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

On Thu, 29 Dec 2022 17:05:45 +0000, Ben Dooks wrote:
> If the get_user(x, ptr) has x as a pointer, then the setting
> of (x) = 0 is going to produce the following sparse warning,
> so fix this by forcing the type of 'x' when access_ok() fails.
> 
> fs/aio.c:2073:21: warning: Using plain integer as NULL pointer
> 
> 
> [...]

Applied, thanks!

[1/1] riscv: uaccess: fix type of 0 variable on error in get_user()
      https://git.kernel.org/palmer/c/b9b916aee671

Best regards,
-- 
Palmer Dabbelt <palmer@rivosinc.com>

On Thu, 29 Dec 2022 09:05:45 PST (-0800), ben-linux@fluff.org wrote:
> If the get_user(x, ptr) has x as a pointer, then the setting
> of (x) = 0 is going to produce the following sparse warning,
> so fix this by forcing the type of 'x' when access_ok() fails.
>
> fs/aio.c:2073:21: warning: Using plain integer as NULL pointer
>
> Signed-off-by: Ben Dooks <ben-linux@fluff.org>
> ---
>  arch/riscv/include/asm/uaccess.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
> index 855450bed9f5..ec0cab9fbddd 100644
> --- a/arch/riscv/include/asm/uaccess.h
> +++ b/arch/riscv/include/asm/uaccess.h
> @@ -165,7 +165,7 @@ do {								\
>  	might_fault();						\
>  	access_ok(__p, sizeof(*__p)) ?		\
>  		__get_user((x), __p) :				\
> -		((x) = 0, -EFAULT);				\
> +		((x) = (__force __typeof__(x))0, -EFAULT);	\
>  })
>
>  #define __put_user_asm(insn, x, ptr, err)			\

Looks like arm64 has a pretty similar pattern.  They've got the __force 
__typeof__ already, but given the similarity it might be worth 
refactoring these to share the error checking code.

Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>

I'll give this a bit of time like usual, unless anyone's opposed I'll 
put it on fixes.  I wasn't planning on sending a PR this week anyway due 
to the holidays.

Thanks!

On Thu, Dec 29, 2022 at 09:31:27AM -0800, Palmer Dabbelt wrote:
> On Thu, 29 Dec 2022 09:05:45 PST (-0800), ben-linux@fluff.org wrote:
> > If the get_user(x, ptr) has x as a pointer, then the setting
> > of (x) = 0 is going to produce the following sparse warning,
> > so fix this by forcing the type of 'x' when access_ok() fails.
> > 
> > fs/aio.c:2073:21: warning: Using plain integer as NULL pointer
> > 
> > Signed-off-by: Ben Dooks <ben-linux@fluff.org>
> > ---
> >  arch/riscv/include/asm/uaccess.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
> > index 855450bed9f5..ec0cab9fbddd 100644
> > --- a/arch/riscv/include/asm/uaccess.h
> > +++ b/arch/riscv/include/asm/uaccess.h
> > @@ -165,7 +165,7 @@ do {								\
> >  	might_fault();						\
> >  	access_ok(__p, sizeof(*__p)) ?		\
> >  		__get_user((x), __p) :				\
> > -		((x) = 0, -EFAULT);				\
> > +		((x) = (__force __typeof__(x))0, -EFAULT);	\
> >  })
> > 
> >  #define __put_user_asm(insn, x, ptr, err)			\
> 
> Looks like arm64 has a pretty similar pattern.  They've got the __force
> __typeof__ already, but given the similarity it might be worth refactoring
> these to share the error checking code.

I looked there for an idea on how to fix.

> Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
> 
> I'll give this a bit of time like usual, unless anyone's opposed I'll put it
> on fixes.  I wasn't planning on sending a PR this week anyway due to the
> holidays.

Ok, it's a warning which would be nice to be fixed.

-- 
Ben Dooks, ben@fluff.org, http://www.fluff.org/ben/

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