diff mbox series

[v5,12/15] x86, module: Ignore __typeid__ relocations

Message ID 20211013181658.1020262-13-samitolvanen@google.com (mailing list archive)
State Changes Requested
Headers show
Series x86: Add support for Clang CFI | expand

Commit Message

Sami Tolvanen Oct. 13, 2021, 6:16 p.m. UTC 
The R_X86_64_8 __typeid__* relocations are for constants the compiler
generates for indirect call type checking with CONFIG_CFI_CLANG. Ignore
them when loading modules.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
---
 arch/x86/kernel/module.c | 4 ++++
 1 file changed, 4 insertions(+)

Comments

Kees Cook Oct. 13, 2021, 6:55 p.m. UTC | #1 
On Wed, Oct 13, 2021 at 11:16:55AM -0700, Sami Tolvanen wrote:
> The R_X86_64_8 __typeid__* relocations are for constants the compiler
> generates for indirect call type checking with CONFIG_CFI_CLANG. Ignore
> them when loading modules.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>
diff mbox series

Patch

diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index 5e9a34b5bd74..c4aeba237eef 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -197,6 +197,10 @@  static int __apply_relocate_add(Elf64_Shdr *sechdrs,
 			val -= (u64)loc;
 			write(loc, &val, 8);
 			break;
+		case R_X86_64_8:
+			if (!strncmp(strtab + sym->st_name, "__typeid__", 10))
+				break;
+			fallthrough;
 		default:
 			pr_err("%s: Unknown rela relocation: %llu\n",
 			       me->name, ELF64_R_TYPE(rel[i].r_info));