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authorKees Cook <keescook@chromium.org>2016-05-02 15:51:01 -0700
committerIngo Molnar <mingo@kernel.org>2016-05-03 08:15:58 +0200
commit00ec2c37031eb1b1feda006c84748d126dc2ef27 (patch)
treed9e9ed4585ad2a3e15e46dab6f3027ae91394f00 /arch/x86/boot
parentdc425a6e140bca99bdb4823e9909c9d9b8ba36b6 (diff)
downloadlinux-00ec2c37031eb1b1feda006c84748d126dc2ef27.tar.bz2
x86/boot: Warn on future overlapping memcpy() use
If an overlapping memcpy() is ever attempted, we should at least report it, in case it might lead to problems, so it could be changed to a memmove() call instead. Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Baoquan He <bhe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bp@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Lasse Collin <lasse.collin@tukaani.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yinghai Lu <yinghai@kernel.org> Link: http://lkml.kernel.org/r/1462229461-3370-3-git-send-email-keescook@chromium.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/boot')
-rw-r--r--arch/x86/boot/compressed/string.c16
1 files changed, 13 insertions, 3 deletions
diff --git a/arch/x86/boot/compressed/string.c b/arch/x86/boot/compressed/string.c
index faa4dc7dc66b..cea140ce6b42 100644
--- a/arch/x86/boot/compressed/string.c
+++ b/arch/x86/boot/compressed/string.c
@@ -10,7 +10,7 @@
#include "../string.c"
#ifdef CONFIG_X86_32
-void *memcpy(void *dest, const void *src, size_t n)
+static void *__memcpy(void *dest, const void *src, size_t n)
{
int d0, d1, d2;
asm volatile(
@@ -24,7 +24,7 @@ void *memcpy(void *dest, const void *src, size_t n)
return dest;
}
#else
-void *memcpy(void *dest, const void *src, size_t n)
+static void *__memcpy(void *dest, const void *src, size_t n)
{
long d0, d1, d2;
asm volatile(
@@ -55,10 +55,20 @@ void *memmove(void *dest, const void *src, size_t n)
const unsigned char *s = src;
if (d <= s || d - s >= n)
- return memcpy(dest, src, n);
+ return __memcpy(dest, src, n);
while (n-- > 0)
d[n] = s[n];
return dest;
}
+
+/* Detect and warn about potential overlaps, but handle them with memmove. */
+void *memcpy(void *dest, const void *src, size_t n)
+{
+ if (dest > src && dest - src < n) {
+ warn("Avoiding potentially unsafe overlapping memcpy()!");
+ return memmove(dest, src, n);
+ }
+ return __memcpy(dest, src, n);
+}