* [PATCH] ELF, uapi: fixup ELF_ST_TYPE definition
@ 2022-04-29 14:50 Alexey Dobriyan
2022-04-29 17:25 ` Kees Cook
0 siblings, 1 reply; 3+ messages in thread
From: Alexey Dobriyan @ 2022-04-29 14:50 UTC (permalink / raw)
To: akpm; +Cc: linux-kernel, linux-api
This is very theoretical compile failure:
ELF_ST_TYPE(st_info = A)
Cast will bind first and st_info will stop being lvalue:
error: lvalue required as left operand of assignment
Given that the only use of this macro is
ELF_ST_TYPE(sym->st_info)
where st_info is "unsigned char" I've decided to remove cast especially
given that companion macro ELF_ST_BIND doesn't use cast.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
include/uapi/linux/elf.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/include/uapi/linux/elf.h
+++ b/include/uapi/linux/elf.h
@@ -134,7 +134,7 @@ typedef __s64 Elf64_Sxword;
#define STT_TLS 6
#define ELF_ST_BIND(x) ((x) >> 4)
-#define ELF_ST_TYPE(x) (((unsigned int) x) & 0xf)
+#define ELF_ST_TYPE(x) ((x) & 0xf)
#define ELF32_ST_BIND(x) ELF_ST_BIND(x)
#define ELF32_ST_TYPE(x) ELF_ST_TYPE(x)
#define ELF64_ST_BIND(x) ELF_ST_BIND(x)
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] ELF, uapi: fixup ELF_ST_TYPE definition
2022-04-29 14:50 [PATCH] ELF, uapi: fixup ELF_ST_TYPE definition Alexey Dobriyan
@ 2022-04-29 17:25 ` Kees Cook
2022-04-29 18:02 ` Alexey Dobriyan
0 siblings, 1 reply; 3+ messages in thread
From: Kees Cook @ 2022-04-29 17:25 UTC (permalink / raw)
To: Alexey Dobriyan; +Cc: akpm, linux-kernel, Eric Biederman, linux-api
On Fri, Apr 29, 2022 at 05:50:03PM +0300, Alexey Dobriyan wrote:
> This is very theoretical compile failure:
>
> ELF_ST_TYPE(st_info = A)
>
> Cast will bind first and st_info will stop being lvalue:
>
> error: lvalue required as left operand of assignment
>
> Given that the only use of this macro is
>
> ELF_ST_TYPE(sym->st_info)
>
> where st_info is "unsigned char" I've decided to remove cast especially
> given that companion macro ELF_ST_BIND doesn't use cast.
>
> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
> ---
>
> include/uapi/linux/elf.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
It looks like akpm already pulled this, so:
Acked-by: Kees Cook <keescook@chromium.org>
Please keep Eric & I CCed on ELF changes; there's a MAINTAINERS entry
now...
-Kees
--
Kees Cook
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-04-29 14:50 [PATCH] ELF, uapi: fixup ELF_ST_TYPE definition Alexey Dobriyan
2022-04-29 17:25 ` Kees Cook
2022-04-29 18:02 ` Alexey Dobriyan
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