1 files changed, 11 insertions, 2 deletions

diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c
index 4f14b5ce6535..80254b47dc34 100644
--- a/arch/arm/kernel/module.c
+++ b/arch/arm/kernel/module.c
@@ -155,8 +155,17 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
                        break;
 
                 case R_ARM_PREL31:
-                        offset = *(u32 *)loc + sym->st_value - loc;
-                        *(u32 *)loc = offset & 0x7fffffff;
+                        offset = (*(s32 *)loc << 1) >> 1; /* sign extend */
+                        offset += sym->st_value - loc;
+                        if (offset >= 0x40000000 || offset < -0x40000000) {
+                                pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
+                                       module->name, relindex, i, symname,
+                                       ELF32_R_TYPE(rel->r_info), loc,
+                                       sym->st_value);
+                                return -ENOEXEC;
+                        }
+                        *(u32 *)loc &= 0x80000000;
+                        *(u32 *)loc |= offset & 0x7fffffff;
                         break;
 
                 case R_ARM_MOVW_ABS_NC: