[PATCH v2] m32r: test before subtraction on unsigned relocation range

Roel Kluin
2008-04-25T08:45:36Z

Hirokazu Takata wrote:
> From: Roel Kluin <12o3l@tiscali.nl>
> Subject: [PATCH] m32r: test before subtraction on unsigned relocation range
> Date: Wed, 23 Apr 2008 18:34:16 +0200
>> case R_M32R_26_PCREL_RELA:
>> - relocation = (relocation - (Elf32_Addr) location);
>> - if (relocation < -0x2000000 || 0x1fffffc < relocation)
>> + if (relocation + 0x20000 < (Elf32_Addr) location ||
>> + relocation >= 0x1fffc + (Elf32_Addr) location)
>
> A slight fix is required.
>
> The above range check is incorrect, because the R_M32R_26_PCREL_RELA is
> 26-bit relocation.
>
> -- Takata
>
Thanks for spotting this!
---
Relocation is unsigned, test before subtraction

Signed-off-by: Roel Kluin <12o3l@tiscali.nl>
---
diff --git a/arch/m32r/kernel/module.c b/arch/m32r/kernel/module.c
index 8d42057..947def6 100644
--- a/arch/m32r/kernel/module.c
+++ b/arch/m32r/kernel/module.c
@@ -171,13 +171,14 @@ int apply_relocate_add(Elf32_Shdr *sechdrs,
COPY_UNALIGNED_WORD (value, *location, align);
break;
case R_M32R_18_PCREL_RELA:
- relocation = (relocation - (Elf32_Addr) location);
- if (relocation < -0x20000 || 0x1fffc < relocation)
+ if (relocation + 0x20000 < (Elf32_Addr) location ||
+ relocation >= 0x1fffc + (Elf32_Addr) location)
{
printk(KERN_ERR "module %s: relocation overflow: %u\n",
- me->name, relocation);
+ me->name, relocation - (Elf32_Addr) location));
return -ENOEXEC;
}
+ relocation = (relocation - (Elf32_Addr) location);
COPY_UNALIGNED_WORD (*location, value, align);
if (value & 0xffff)
{
@@ -203,13 +204,14 @@ int apply_relocate_add(Elf32_Shdr *sechdrs,
COPY_UNALIGNED_HWORD (hvalue, *hlocation, align);
break;
case R_M32R_26_PCREL_RELA:
- relocation = (relocation - (Elf32_Addr) location);
- if (relocation < -0x2000000 || 0x1fffffc < relocation)
+ if (relocation + 0x2000000 < (Elf32_Addr) location ||