Commit-ID: bf0118dbba9542ceb5d33d4a86830a6c88b0bbf6 Gitweb: http://git.kernel.org/tip/bf0118dbba9542ceb5d33d4a86830a6c88b0bbf6 Author: Kees Cook <[email protected]> AuthorDate: Wed, 20 Apr 2016 13:55:45 -0700 Committer: Ingo Molnar <[email protected]> CommitDate: Fri, 22 Apr 2016 10:00:50 +0200
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 <[email protected]> Reported-by: Yinghai Lu <[email protected]> Signed-off-by: Kees Cook <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Andrey Ryabinin <[email protected]> Cc: Andy Lutomirski <[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: Dmitry Vyukov <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: H.J. Lu <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/boot/compressed/misc.c | 4 +--- arch/x86/boot/compressed/string.c | 22 ++++++++++++++++++++-- 2 files changed, 21 insertions(+), 5 deletions(-) diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c index 0381e25..eacc855 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 00e788b..1e10e40 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; +}
