[PATCH v6 23/29] x86/build: Enforce an empty .got.plt section
From: Kees Cook <hidden>
Date: 2020-08-21 19:45:31
Also in:
linux-arch, linux-efi, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
The .got.plt section should always be zero (or filled only with the linker-generated lazy dispatch entry). Enforce this with an assert and mark the section as INFO. This is more sensitive than just blindly discarding the section. Signed-off-by: Kees Cook <redacted> --- arch/x86/kernel/vmlinux.lds.S | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 0cc035cb15f1..4b1b936a6e7d 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S@@ -414,8 +414,20 @@ SECTIONS ELF_DETAILS DISCARDS -} + /* + * Make sure that the .got.plt is either completely empty or it + * contains only the lazy dispatch entries. + */ + .got.plt (INFO) : { *(.got.plt) } + ASSERT(SIZEOF(.got.plt) == 0 || +#ifdef CONFIG_X86_64 + SIZEOF(.got.plt) == 0x18, +#else + SIZEOF(.got.plt) == 0xc, +#endif + "Unexpected GOT/PLT entries detected!") +} #ifdef CONFIG_X86_32 /*
--
2.25.1
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