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authorKees Cook2016-04-20 13:55:45 -0700
committerIngo Molnar2016-04-22 10:00:50 +0200
commitbf0118dbba9542ceb5d33d4a86830a6c88b0bbf6 (patch)
tree04628ab4122802bed574b2e47bc66294cdeced5b
parent1f208de37d10bb9067f3b061d281363be0cd1805 (diff)
x86/boot: Make memcpy() handle overlaps
Two uses of memcpy() (screen scrolling and ELF parsing) were handling overlapping memory areas. While there were no explicitly noticed bugs here (yet), it is best to fix this so that the copying will always be safe. Instead of making a new memmove() function that might collide with other memmove() definitions in the decompressors, this just makes the compressed boot code's copy of memcpy() overlap-safe. Suggested-by: Lasse Collin <lasse.collin@tukaani.org> Reported-by: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> 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: Dmitry Vyukov <dvyukov@google.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: H.J. Lu <hjl.tools@gmail.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1461185746-8017-5-git-send-email-keescook@chromium.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--arch/x86/boot/compressed/misc.c4
-rw-r--r--arch/x86/boot/compressed/string.c22
2 files changed, 21 insertions, 5 deletions
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index 0381e250a785..eacc855ae08e 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -301,9 +301,7 @@ 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/string.c b/arch/x86/boot/compressed/string.c
index 00e788be1db9..1e10e40f49dd 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(
@@ -39,3 +39,21 @@ void *memset(void *s, int c, size_t n)
ss[i] = c;
return s;
}
+
+/*
+ * This memcpy is overlap safe (i.e. it is memmove without conflicting
+ * with other definitions of memmove from the various decompressors.
+ */
+void *memcpy(void *dest, const void *src, size_t n)
+{
+ unsigned char *d = dest;
+ const unsigned char *s = src;
+
+ if (d <= s || d - s >= n)
+ return __memcpy(dest, src, n);
+
+ while (n-- > 0)
+ d[n] = s[n];
+
+ return dest;
+}