From: Kees Cook keescook@chromium.org
[ Upstream commit 072af0c638dc8a5c7db2edc4dddbd6d44bee3bdb ]
The implementation for intra-object overflow in str*-family functions accidentally dropped compile-time write overflow checking in strcpy(), leaving it entirely to run-time. Add back the intended check.
Fixes: 6a39e62abbaf ("lib: string.h: detect intra-object overflow in fortified string functions") Cc: Daniel Axtens dja@axtens.net Cc: Francis Laniel laniel_francis@privacyrequired.com Signed-off-by: Kees Cook keescook@chromium.org Reviewed-by: Nick Desaulniers ndesaulniers@google.com Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/fortify-string.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h index c1be37437e778..0c70febd03e95 100644 --- a/include/linux/fortify-string.h +++ b/include/linux/fortify-string.h @@ -280,7 +280,10 @@ __FORTIFY_INLINE char *strcpy(char *p, const char *q) if (p_size == (size_t)-1 && q_size == (size_t)-1) return __underlying_strcpy(p, q); size = strlen(q) + 1; - /* test here to use the more stringent object size */ + /* Compile-time check for const size overflow. */ + if (__builtin_constant_p(size) && p_size < size) + __write_overflow(); + /* Run-time check for dynamic size overflow. */ if (p_size < size) fortify_panic(__func__); memcpy(p, q, size);