x86/module: Detect and skip invalid relocations

[sfrench/cifs-2.6.git] / arch / x86 / kernel / module.c

diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index 62e7d70aadd5ffece72b357ac1e3024a1b9f7897..da0c160e558905c2164bf1d3879bd1a1cf368f34 100644 (file)
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -172,19 +172,27 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
                case R_X86_64_NONE:
                        break;
                case R_X86_64_64:
+                       if (*(u64 *)loc != 0)
+                               goto invalid_relocation;
                        *(u64 *)loc = val;
                        break;
                case R_X86_64_32:
+                       if (*(u32 *)loc != 0)
+                               goto invalid_relocation;
                        *(u32 *)loc = val;
                        if (val != *(u32 *)loc)
                                goto overflow;
                        break;
                case R_X86_64_32S:
+                       if (*(s32 *)loc != 0)
+                               goto invalid_relocation;
                        *(s32 *)loc = val;
                        if ((s64)val != *(s32 *)loc)
                                goto overflow;
                        break;
                case R_X86_64_PC32:
+                       if (*(u32 *)loc != 0)
+                               goto invalid_relocation;
                        val -= (u64)loc;
                        *(u32 *)loc = val;
 #if 0
@@ -200,6 +208,11 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
        }
        return 0;
 
+invalid_relocation:
+       pr_err("x86/modules: Skipping invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n",
+              (int)ELF64_R_TYPE(rel[i].r_info), loc, val);
+       return -ENOEXEC;
+
 overflow:
        pr_err("overflow in relocation type %d val %Lx\n",
               (int)ELF64_R_TYPE(rel[i].r_info), val);