Define vdso_start, vdso_end as array to avoid compile-time analysis error
for the case of built with CONFIG_FORTIFY_SOURCE.
and, since vdso_start, vdso_end are used in vdso.c only,
move extern-declaration from vdso.h to vdso.c.
If kernel is built with CONFIG_FORTIFY_SOURCE,
compile-time error happens at this code.
- if (memcmp(&vdso_start, "\177ELF", 4))
The size of "&vdso_start" is recognized as 1 byte, but n is 4,
So that compile-time error is reported.
Signed-off-by: Jinbum Park <[email protected]>
---
arch/arm/include/asm/vdso.h | 2 --
arch/arm/kernel/vdso.c | 12 +++++++-----
2 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/arch/arm/include/asm/vdso.h b/arch/arm/include/asm/vdso.h
index 9c99e81..5b85889 100644
--- a/arch/arm/include/asm/vdso.h
+++ b/arch/arm/include/asm/vdso.h
@@ -12,8 +12,6 @@
void arm_install_vdso(struct mm_struct *mm, unsigned long addr);
-extern char vdso_start, vdso_end;
-
extern unsigned int vdso_total_pages;
#else /* CONFIG_VDSO */
diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c
index a4d6dc0..f4dd7f9 100644
--- a/arch/arm/kernel/vdso.c
+++ b/arch/arm/kernel/vdso.c
@@ -39,6 +39,8 @@
static struct page **vdso_text_pagelist;
+extern char vdso_start[], vdso_end[];
+
/* Total number of pages needed for the data and text portions of the VDSO. */
unsigned int vdso_total_pages __ro_after_init;
@@ -197,13 +199,13 @@ static int __init vdso_init(void)
unsigned int text_pages;
int i;
- if (memcmp(&vdso_start, "\177ELF", 4)) {
+ if (memcmp(vdso_start, "\177ELF", 4)) {
pr_err("VDSO is not a valid ELF object!\n");
return -ENOEXEC;
}
- text_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT;
- pr_debug("vdso: %i text pages at base %p\n", text_pages, &vdso_start);
+ text_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
+ pr_debug("vdso: %i text pages at base %p\n", text_pages, vdso_start);
/* Allocate the VDSO text pagelist */
vdso_text_pagelist = kcalloc(text_pages, sizeof(struct page *),
@@ -218,7 +220,7 @@ static int __init vdso_init(void)
for (i = 0; i < text_pages; i++) {
struct page *page;
- page = virt_to_page(&vdso_start + i * PAGE_SIZE);
+ page = virt_to_page(vdso_start + i * PAGE_SIZE);
vdso_text_pagelist[i] = page;
}
@@ -229,7 +231,7 @@ static int __init vdso_init(void)
cntvct_ok = cntvct_functional();
- patch_vdso(&vdso_start);
+ patch_vdso(vdso_start);
return 0;
}
--
1.9.1
On Wed, Feb 28, 2018 at 6:29 AM, Jinbum Park <[email protected]> wrote:
> Define vdso_start, vdso_end as array to avoid compile-time analysis error
> for the case of built with CONFIG_FORTIFY_SOURCE.
>
> and, since vdso_start, vdso_end are used in vdso.c only,
> move extern-declaration from vdso.h to vdso.c.
>
> If kernel is built with CONFIG_FORTIFY_SOURCE,
> compile-time error happens at this code.
> - if (memcmp(&vdso_start, "\177ELF", 4))
>
> The size of "&vdso_start" is recognized as 1 byte, but n is 4,
> So that compile-time error is reported.
>
> Signed-off-by: Jinbum Park <[email protected]>
Thanks!
Acked-by: Kees Cook <[email protected]>
-Kees
> ---
> arch/arm/include/asm/vdso.h | 2 --
> arch/arm/kernel/vdso.c | 12 +++++++-----
> 2 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm/include/asm/vdso.h b/arch/arm/include/asm/vdso.h
> index 9c99e81..5b85889 100644
> --- a/arch/arm/include/asm/vdso.h
> +++ b/arch/arm/include/asm/vdso.h
> @@ -12,8 +12,6 @@
>
> void arm_install_vdso(struct mm_struct *mm, unsigned long addr);
>
> -extern char vdso_start, vdso_end;
> -
> extern unsigned int vdso_total_pages;
>
> #else /* CONFIG_VDSO */
> diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c
> index a4d6dc0..f4dd7f9 100644
> --- a/arch/arm/kernel/vdso.c
> +++ b/arch/arm/kernel/vdso.c
> @@ -39,6 +39,8 @@
>
> static struct page **vdso_text_pagelist;
>
> +extern char vdso_start[], vdso_end[];
> +
> /* Total number of pages needed for the data and text portions of the VDSO. */
> unsigned int vdso_total_pages __ro_after_init;
>
> @@ -197,13 +199,13 @@ static int __init vdso_init(void)
> unsigned int text_pages;
> int i;
>
> - if (memcmp(&vdso_start, "\177ELF", 4)) {
> + if (memcmp(vdso_start, "\177ELF", 4)) {
> pr_err("VDSO is not a valid ELF object!\n");
> return -ENOEXEC;
> }
>
> - text_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT;
> - pr_debug("vdso: %i text pages at base %p\n", text_pages, &vdso_start);
> + text_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
> + pr_debug("vdso: %i text pages at base %p\n", text_pages, vdso_start);
>
> /* Allocate the VDSO text pagelist */
> vdso_text_pagelist = kcalloc(text_pages, sizeof(struct page *),
> @@ -218,7 +220,7 @@ static int __init vdso_init(void)
> for (i = 0; i < text_pages; i++) {
> struct page *page;
>
> - page = virt_to_page(&vdso_start + i * PAGE_SIZE);
> + page = virt_to_page(vdso_start + i * PAGE_SIZE);
> vdso_text_pagelist[i] = page;
> }
>
> @@ -229,7 +231,7 @@ static int __init vdso_init(void)
>
> cntvct_ok = cntvct_functional();
>
> - patch_vdso(&vdso_start);
> + patch_vdso(vdso_start);
>
> return 0;
> }
> --
> 1.9.1
>
--
Kees Cook
Pixel Security