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From: Kees Cook <keescook@chromium.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>,
	Daniel Micay <danielmicay@gmail.com>,
	linux-kernel@vger.kernel.org,
	Stephen Rothwell <sfr@canb.auug.org.au>
Subject: [PATCH 3/7] kexec_file: Adjust declaration of kexec_purgatory
Date: Mon, 19 Jun 2017 13:26:23 -0700
Message-ID: <1497903987-21002-4-git-send-email-keescook@chromium.org> (raw)
In-Reply-To: <1497903987-21002-1-git-send-email-keescook@chromium.org>

Defining kexec_purgatory as a zero-length char array upsets compile
time size checking. Since this is built on a per-arch basis, define
it as an unsized char array (like is done for other similar things,
e.g. linker sections). This silences the warning generated by the future
CONFIG_FORTIFY_SOURCE, which did not like the memcmp() of a "0 byte"
array. This drops the __weak and uses an extern instead, since both
users define kexec_purgatory.

Cc: Daniel Micay <danielmicay@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 kernel/kexec_file.c     | 7 -------
 kernel/kexec_internal.h | 2 ++
 2 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index b118735fea9d..7a147a7add2e 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -26,13 +26,6 @@
 #include <linux/vmalloc.h>
 #include "kexec_internal.h"
 
-/*
- * Declare these symbols weak so that if architecture provides a purgatory,
- * these will be overridden.
- */
-char __weak kexec_purgatory[0];
-size_t __weak kexec_purgatory_size = 0;
-
 static int kexec_calculate_store_digests(struct kimage *image);
 
 /* Architectures can provide this probe function */
diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
index 799a8a452187..50dfcb039a41 100644
--- a/kernel/kexec_internal.h
+++ b/kernel/kexec_internal.h
@@ -17,6 +17,8 @@ extern struct mutex kexec_mutex;
 #ifdef CONFIG_KEXEC_FILE
 #include <linux/purgatory.h>
 void kimage_file_post_load_cleanup(struct kimage *image);
+extern char kexec_purgatory[];
+extern size_t kexec_purgatory_size;
 #else /* CONFIG_KEXEC_FILE */
 static inline void kimage_file_post_load_cleanup(struct kimage *image) { }
 #endif /* CONFIG_KEXEC_FILE */
-- 
2.7.4

  parent reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-19 20:26 [PATCH 0/7] CONFIG_FORTIFY_SOURCE Kees Cook
2017-06-19 20:26 ` [PATCH 1/7] efi: Avoid fortify checks in EFI stub Kees Cook
2017-06-19 20:26 ` [PATCH 2/7] x86/power/64: Use char arrays for asm function names Kees Cook
2017-06-19 20:26 ` Kees Cook [this message]
2017-06-19 20:26 ` [PATCH 4/7] IB/rxe: Do not copy extra stack memory to skb Kees Cook
2017-06-19 20:26 ` [PATCH 5/7] powerpc: Don't fortify prom_init Kees Cook
2017-06-19 20:26 ` [PATCH 6/7] powerpc: Make feature-fixup tests fortify-safe Kees Cook
2017-06-19 20:26 ` [PATCH 7/7] include/linux/string.h: add the option of fortified string.h functions Kees Cook
2017-09-10 10:55   ` Geert Uytterhoeven
2017-09-10 13:51     ` Arnd Bergmann
2017-06-19 21:50 ` [PATCH 0/7] CONFIG_FORTIFY_SOURCE Andrew Morton
2017-06-19 22:12   ` Kees Cook
2017-06-19 22:31     ` Andrew Morton

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