2021-06-18 14:09:34

by Jisheng Zhang

Subject: [PATCH] riscv: kasan: Fix MODULES_VADDR evaluation due to local variables' name

From: Jisheng Zhang <[email protected]>

commit 2bfc6cd81bd1 ("riscv: Move kernel mapping outside of linear
mapping") makes use of MODULES_VADDR to populate kernel, BPF, modules
mapping. Currently, MODULES_VADDR is defined as below for RV64:

| #define MODULES_VADDR (PFN_ALIGN((unsigned long)&_end) - SZ_2G)

But kasan_init() has two local variables which are also named as _start,
_end, so MODULES_VADDR is evaluated with the local variable _end
rather than the global "_end" as we expected. Fix this issue by
renaming the two local variables.

Fixes: 2bfc6cd81bd1 ("riscv: Move kernel mapping outside of linear mapping")
Signed-off-by: Jisheng Zhang <[email protected]>
---
arch/riscv/mm/kasan_init.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
index 55c113345460..d7189c8714a9 100644
--- a/arch/riscv/mm/kasan_init.c
+++ b/arch/riscv/mm/kasan_init.c
@@ -169,7 +169,7 @@ static void __init kasan_shallow_populate(void *start, void *end)

void __init kasan_init(void)
{
- phys_addr_t _start, _end;
+ phys_addr_t p_start, p_end;
u64 i;

/*
@@ -189,9 +189,9 @@ void __init kasan_init(void)
(void *)kasan_mem_to_shadow((void *)VMALLOC_END));

/* Populate the linear mapping */
- for_each_mem_range(i, &_start, &_end) {
- void *start = (void *)__va(_start);
- void *end = (void *)__va(_end);
+ for_each_mem_range(i, &p_start, &p_end) {
+ void *start = (void *)__va(p_start);
+ void *end = (void *)__va(p_end);

if (start >= end)
break;
--
2.32.0

2021-06-19 10:00:45

by Palmer Dabbelt

Subject: Re: [PATCH] riscv: kasan: Fix MODULES_VADDR evaluation due to local variables' name

On Fri, 18 Jun 2021 07:01:36 PDT (-0700), [email protected] wrote:
> From: Jisheng Zhang <[email protected]>
>
> commit 2bfc6cd81bd1 ("riscv: Move kernel mapping outside of linear
> mapping") makes use of MODULES_VADDR to populate kernel, BPF, modules
> mapping. Currently, MODULES_VADDR is defined as below for RV64:
>
> | #define MODULES_VADDR (PFN_ALIGN((unsigned long)&_end) - SZ_2G)
>
> But kasan_init() has two local variables which are also named as _start,
> _end, so MODULES_VADDR is evaluated with the local variable _end
> rather than the global "_end" as we expected. Fix this issue by
> renaming the two local variables.
>
> Fixes: 2bfc6cd81bd1 ("riscv: Move kernel mapping outside of linear mapping")
> Signed-off-by: Jisheng Zhang <[email protected]>
> ---
> arch/riscv/mm/kasan_init.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
> index 55c113345460..d7189c8714a9 100644
> --- a/arch/riscv/mm/kasan_init.c
> +++ b/arch/riscv/mm/kasan_init.c
> @@ -169,7 +169,7 @@ static void __init kasan_shallow_populate(void *start, void *end)
>
> void __init kasan_init(void)
> {
> - phys_addr_t _start, _end;
> + phys_addr_t p_start, p_end;
> u64 i;
>
> /*
> @@ -189,9 +189,9 @@ void __init kasan_init(void)
> (void *)kasan_mem_to_shadow((void *)VMALLOC_END));
>
> /* Populate the linear mapping */
> - for_each_mem_range(i, &_start, &_end) {
> - void *start = (void *)__va(_start);
> - void *end = (void *)__va(_end);
> + for_each_mem_range(i, &p_start, &p_end) {
> + void *start = (void *)__va(p_start);
> + void *end = (void *)__va(p_end);
>
> if (start >= end)
> break;

Thanks for this. I'd prefer a cleaner fix for tihs (maybe more '_'s in
_end?), but I don't think we can do that without touching a bunch of
code. Given that this is necessary to make the fix work for me, I'm
just going to take it as-is.

This is on fixes.