From c72241a70cc4b849a7f3f346ec0c052f7da711a7 Mon Sep 17 00:00:00 2001 From: Joe Lawrence Date: Fri, 16 Sep 2022 18:47:56 +0800 Subject: [PATCH] objtool: Make .altinstructions section entry size consistent stable inclusion from stable-v5.10.133 commit e8b1128fb0d6aa97420d5012ab9f62ad262f8f77 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5PTAS CVE: CVE-2022-29900,CVE-2022-23816,CVE-2022-29901 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e8b1128fb0d6aa97420d5012ab9f62ad262f8f77 -------------------------------- commit dc02368164bd0ec603e3f5b3dd8252744a667b8a upstream. Commit e31694e0a7a7 ("objtool: Don't make .altinstructions writable") aligned objtool-created and kernel-created .altinstructions section flags, but there remains a minor discrepency in their use of a section entry size: objtool sets one while the kernel build does not. While sh_entsize of sizeof(struct alt_instr) seems intuitive, this small deviation can cause failures with external tooling (kpatch-build). Fix this by creating new .altinstructions sections with sh_entsize of 0 and then later updating sec->sh_size as alternatives are added to the section. An added benefit is avoiding the data descriptor and buffer created by elf_create_section(), but previously unused by elf_add_alternative(). Fixes: 9bc0bb50727c ("objtool/x86: Rewrite retpoline thunk calls") Signed-off-by: Joe Lawrence Reviewed-by: Miroslav Benes Signed-off-by: Josh Poimboeuf Link: https://lore.kernel.org/r/20210822225037.54620-2-joe.lawrence@redhat.com Cc: Andy Lavr Cc: Peter Zijlstra Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman Signed-off-by: Lin Yujun Signed-off-by: Zheng Zengkai --- tools/objtool/arch/x86/decode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index b1feb45cf215..99b47720dce9 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -611,7 +611,7 @@ static int elf_add_alternative(struct elf *elf, sec = find_section_by_name(elf, ".altinstructions"); if (!sec) { sec = elf_create_section(elf, ".altinstructions", - SHF_ALLOC, size, 0); + SHF_ALLOC, 0, 0); if (!sec) { WARN_ELF("elf_create_section"); -- GitLab