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Message-Id: <1460672954-32567-14-git-send-email-keescook@chromium.org>
Date: Thu, 14 Apr 2016 15:29:06 -0700
From: Kees Cook <keescook@...omium.org>
To: Ingo Molnar <mingo@...nel.org>
Cc: Kees Cook <keescook@...omium.org>,
Yinghai Lu <yinghai@...nel.org>,
Baoquan He <bhe@...hat.com>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>,
Matt Redfearn <matt.redfearn@...tec.com>,
x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>,
Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
Vivek Goyal <vgoyal@...hat.com>,
Andy Lutomirski <luto@...nel.org>,
lasse.collin@...aani.org,
Andrew Morton <akpm@...ux-foundation.org>,
Dave Young <dyoung@...hat.com>,
kernel-hardening@...ts.openwall.com,
LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v5 13/21] x86, boot: Report overlap failures in memcpy
From: Yinghai Lu <yinghai@...nel.org>
parse_elf is using a local memcpy to move sections to their final running
position. However, this memcpy only supports non-overlapping arguments
(or dest < src).
To avoid future hard-to-debug surprises, this adds checking in memcpy to
detect the unhandled condition (which should not be happening currently).
Signed-off-by: Yinghai Lu <yinghai@...nel.org>
Signed-off-by: Baoquan He <bhe@...hat.com>
[kees: rewrote changelog]
Signed-off-by: Kees Cook <keescook@...omium.org>
---
arch/x86/boot/compressed/misc.c | 9 ++-------
arch/x86/boot/compressed/misc.h | 2 ++
arch/x86/boot/compressed/string.c | 29 +++++++++++++++++++++++++++--
3 files changed, 31 insertions(+), 9 deletions(-)
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index 562d647289ac..c47ac162d3bd 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -114,9 +114,6 @@
#undef memset
#define memzero(s, n) memset((s), 0, (n))
-
-static void error(char *m);
-
/*
* This is set up by the setup-routine at boot-time
*/
@@ -243,7 +240,7 @@ void __puthex(unsigned long value)
}
}
-static void error(char *x)
+void error(char *x)
{
error_putstr("\n\n");
error_putstr(x);
@@ -378,9 +375,7 @@ static void parse_elf(void *output)
#else
dest = (void *)(phdr->p_paddr);
#endif
- memcpy(dest,
- output + phdr->p_offset,
- phdr->p_filesz);
+ memcpy(dest, output + phdr->p_offset, phdr->p_filesz);
break;
default: /* Ignore other PT_* */ break;
}
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index 11736a6a6670..39d0e9a53736 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -38,6 +38,8 @@ void __puthex(unsigned long value);
#define error_putstr(__x) __putstr(__x)
#define error_puthex(__x) __puthex(__x)
+void error(char *x);
+
#ifdef CONFIG_X86_VERBOSE_BOOTUP
#define debug_putstr(__x) __putstr(__x)
diff --git a/arch/x86/boot/compressed/string.c b/arch/x86/boot/compressed/string.c
index 00e788be1db9..3a935d0c82a8 100644
--- a/arch/x86/boot/compressed/string.c
+++ b/arch/x86/boot/compressed/string.c
@@ -1,7 +1,7 @@
#include "../string.c"
#ifdef CONFIG_X86_32
-void *memcpy(void *dest, const void *src, size_t n)
+void *__memcpy(void *dest, const void *src, size_t n)
{
int d0, d1, d2;
asm volatile(
@@ -15,7 +15,7 @@ void *memcpy(void *dest, const void *src, size_t n)
return dest;
}
#else
-void *memcpy(void *dest, const void *src, size_t n)
+void *__memcpy(void *dest, const void *src, size_t n)
{
long d0, d1, d2;
asm volatile(
@@ -30,6 +30,31 @@ void *memcpy(void *dest, const void *src, size_t n)
}
#endif
+extern void error(char *x);
+void *memcpy(void *dest, const void *src, size_t n)
+{
+ unsigned long start_dest, end_dest;
+ unsigned long start_src, end_src;
+ unsigned long max_start, min_end;
+
+ if (dest < src)
+ return __memcpy(dest, src, n);
+
+ start_dest = (unsigned long)dest;
+ end_dest = (unsigned long)dest + n;
+ start_src = (unsigned long)src;
+ end_src = (unsigned long)src + n;
+ max_start = (start_dest > start_src) ? start_dest : start_src;
+ min_end = (end_dest < end_src) ? end_dest : end_src;
+
+ if (max_start >= min_end)
+ return __memcpy(dest, src, n);
+
+ error("memcpy does not support overlapping with dest > src!\n");
+
+ return dest;
+}
+
void *memset(void *s, int c, size_t n)
{
int i;
--
2.6.3
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