Commit-ID: 00ec2c37031eb1b1feda006c84748d126dc2ef27 Gitweb: http://git.kernel.org/tip/00ec2c37031eb1b1feda006c84748d126dc2ef27 Author: Kees Cook <[email protected]> AuthorDate: Mon, 2 May 2016 15:51:01 -0700 Committer: Ingo Molnar <[email protected]> CommitDate: Tue, 3 May 2016 08:15:58 +0200
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 <[email protected]> Signed-off-by: Kees Cook <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Baoquan He <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Lasse Collin <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: One Thousand Gnomes <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Yinghai Lu <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/boot/compressed/string.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/arch/x86/boot/compressed/string.c b/arch/x86/boot/compressed/string.c index faa4dc7..cea140c 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); +}
