From 73aca179d78eaa11604ba0783a6d8b2125fbc332 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Mon, 26 Mar 2018 19:27:01 +1100 Subject: [PATCH] powerpc/modules: Fix crashes by adding CONFIG_RELOCATABLE to vermagic If you build the kernel with CONFIG_RELOCATABLE=n, then install the modules, rebuild the kernel with CONFIG_RELOCATABLE=y and leave the old modules installed, we crash something like: Unable to handle kernel paging request for data at address 0xd000000018d66cef Faulting instruction address: 0xc0000000021ddd08 Oops: Kernel access of bad area, sig: 11 [#1] Modules linked in: x_tables autofs4 CPU: 2 PID: 1 Comm: systemd Not tainted 4.16.0-rc6-gcc_ubuntu_le-g99fec39 #1 ... NIP check_version.isra.22+0x118/0x170 Call Trace: __ksymtab_xt_unregister_table+0x58/0xfffffffffffffcb8 [x_tables] (unreliable) resolve_symbol+0xb4/0x150 load_module+0x10e8/0x29a0 SyS_finit_module+0x110/0x140 system_call+0x58/0x6c This happens because since commit 71810db27c1c ("modversions: treat symbol CRCs as 32 bit quantities"), a relocatable kernel encodes and handles symbol CRCs differently from a non-relocatable kernel. Although it's possible we could try and detect this situation and handle it, it's much more robust to simply make the state of CONFIG_RELOCATABLE part of the module vermagic. Fixes: 71810db27c1c ("modversions: treat symbol CRCs as 32 bit quantities") Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/module.h | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/module.h b/arch/powerpc/include/asm/module.h index 7e28442827f1e6..4f6573934792b9 100644 --- a/arch/powerpc/include/asm/module.h +++ b/arch/powerpc/include/asm/module.h @@ -15,9 +15,19 @@ #ifdef CC_USING_MPROFILE_KERNEL -#define MODULE_ARCH_VERMAGIC "mprofile-kernel" +#define MODULE_ARCH_VERMAGIC_FTRACE "mprofile-kernel " +#else +#define MODULE_ARCH_VERMAGIC_FTRACE "" #endif +#ifdef CONFIG_RELOCATABLE +#define MODULE_ARCH_VERMAGIC_RELOCATABLE "relocatable " +#else +#define MODULE_ARCH_VERMAGIC_RELOCATABLE "" +#endif + +#define MODULE_ARCH_VERMAGIC MODULE_ARCH_VERMAGIC_FTRACE MODULE_ARCH_VERMAGIC_RELOCATABLE + #ifndef __powerpc64__ /* * Thanks to Paul M for explaining this.