From 65c225d3280542f3ea145e052215ce0538f6bb69 Mon Sep 17 00:00:00 2001 From: Philipp Rudo Date: Fri, 13 Apr 2018 15:36:17 -0700 Subject: [PATCH] kernel/kexec_file.c: make purgatory_info->ehdr const The kexec_purgatory buffer is read-only. Thus all pointers into kexec_purgatory are read-only, too. Point this out by explicitly marking purgatory_info->ehdr as 'const' and update the comments in purgatory_info. Link: http://lkml.kernel.org/r/20180321112751.22196-4-prudo@linux.vnet.ibm.com Signed-off-by: Philipp Rudo Acked-by: Dave Young Cc: AKASHI Takahiro Cc: Eric Biederman Cc: Heiko Carstens Cc: Ingo Molnar Cc: Martin Schwidefsky Cc: Michael Ellerman Cc: Thiago Jung Bauermann Cc: Vivek Goyal Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kexec.h | 17 +++++++++++------ kernel/kexec_file.c | 4 ++-- 2 files changed, 13 insertions(+), 8 deletions(-) diff --git a/include/linux/kexec.h b/include/linux/kexec.h index 08b8b9d00f97..8c5819d1a808 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -99,14 +99,19 @@ struct compat_kexec_segment { #ifdef CONFIG_KEXEC_FILE struct purgatory_info { - /* Pointer to elf header of read only purgatory */ - Elf_Ehdr *ehdr; - - /* Pointer to purgatory sechdrs which are modifiable */ + /* + * Pointer to elf header at the beginning of kexec_purgatory. + * Note: kexec_purgatory is read only + */ + const Elf_Ehdr *ehdr; + /* + * Temporary, modifiable buffer for sechdrs used for relocation. + * This memory can be freed post image load. + */ Elf_Shdr *sechdrs; /* - * Temporary buffer location where purgatory is loaded and relocated - * This memory can be freed post image load + * Temporary, modifiable buffer for stripped purgatory used for + * relocation. This memory can be freed post image load. */ void *purgatory_buf; diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 81ba4f782486..12cf9c9ff0bc 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -941,7 +941,7 @@ int kexec_load_purgatory(struct kimage *image, unsigned long min, if (kexec_purgatory_size <= 0) return -EINVAL; - pi->ehdr = (Elf_Ehdr *)kexec_purgatory; + pi->ehdr = (const Elf_Ehdr *)kexec_purgatory; ret = __kexec_load_purgatory(image, min, max, top_down); if (ret) @@ -965,9 +965,9 @@ out: static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi, const char *name) { + const Elf_Ehdr *ehdr; Elf_Sym *syms; Elf_Shdr *sechdrs; - Elf_Ehdr *ehdr; int i, k; const char *strtab;