Messages in this thread Patch in this message | | | Date | Fri, 29 Apr 2016 09:57:45 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v4] x86/boot: Warn on future overlapping memcpy() use |
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* Kees Cook <keescook@chromium.org> wrote:
> 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> > --- > v4: > - use __memcpy not memcpy since we've already done the check. > v3: > - call memmove in addition to doing the warning > v2: > - warn about overlapping region > --- > arch/x86/boot/compressed/string.c | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-)
I think you'll hate this patch some more:
arch/x86/boot/compressed/string.c:68:3: warning: implicit declaration of function ‘warn’ [-Wimplicit-function-declaration]
:-)
Can we do the trick below? Because misc.h also includes the regular kernel memcpy functions, we can remove the decompressor specific __memcpy() - but the question is, is it safe to do?
If it's not safe to do, we are playing with fire already I suspect:
arch/x86/boot/compressed/cmdline.c:#include "misc.h" arch/x86/boot/compressed/early_serial_console.c:#include "misc.h" arch/x86/boot/compressed/kaslr.c:#include "misc.h" arch/x86/boot/compressed/misc.c:#include "misc.h"
?
Thanks,
Ingo
arch/x86/boot/compressed/string.c | 31 +------------------------------ 1 file changed, 1 insertion(+), 30 deletions(-)
diff --git a/arch/x86/boot/compressed/string.c b/arch/x86/boot/compressed/string.c index 952510976732..f4b95ed4e7a2 100644 --- a/arch/x86/boot/compressed/string.c +++ b/arch/x86/boot/compressed/string.c @@ -6,37 +6,8 @@ * (e.g. FPU ops) in the minimal decompression stub execution environment. */ #include "../string.c" -#include "misc.h" - -#ifdef CONFIG_X86_32 -static void *__memcpy(void *dest, const void *src, size_t n) -{ - int d0, d1, d2; - asm volatile( - "rep ; movsl\n\t" - "movl %4,%%ecx\n\t" - "rep ; movsb\n\t" - : "=&c" (d0), "=&D" (d1), "=&S" (d2) - : "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src) - : "memory"); - - return dest; -} -#else -static void *__memcpy(void *dest, const void *src, size_t n) -{ - long d0, d1, d2; - asm volatile( - "rep ; movsq\n\t" - "movq %4,%%rcx\n\t" - "rep ; movsb\n\t" - : "=&c" (d0), "=&D" (d1), "=&S" (d2) - : "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src) - : "memory"); - return dest; -} -#endif +#include "misc.h" void *memset(void *s, int c, size_t n) {
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