From 65c225d3280542f3ea145e052215ce0538f6bb69 Mon Sep 17 00:00:00 2001
From: Philipp Rudo <prudo@linux.vnet.ibm.com>
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 <prudo@linux.vnet.ibm.com>
Acked-by: Dave Young <dyoung@redhat.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
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 @@ int kexec_load_purgatory(struct kimage *image, unsigned long min,
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;
--
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