From 2d1c89a5d7c872a1109768f50e2508cf9a4b0348 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Wed, 20 Jun 2018 09:45:19 +0200 Subject: libio: Avoid ptrdiff_t overflow in IO_validate_vtable If the candidate pointer is sufficiently far away from __start___libc_IO_vtables, the result might not fit into ptrdiff_t. --- libio/libioP.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'libio') diff --git a/libio/libioP.h b/libio/libioP.h index 8afe703..df2633d 100644 --- a/libio/libioP.h +++ b/libio/libioP.h @@ -830,8 +830,8 @@ IO_validate_vtable (const struct _IO_jump_t *vtable) /* Fast path: The vtable pointer is within the __libc_IO_vtables section. */ uintptr_t section_length = __stop___libc_IO_vtables - __start___libc_IO_vtables; - const char *ptr = (const char *) vtable; - uintptr_t offset = ptr - __start___libc_IO_vtables; + uintptr_t ptr = (uintptr_t) vtable; + uintptr_t offset = ptr - (uintptr_t) __start___libc_IO_vtables; if (__glibc_unlikely (offset >= section_length)) /* The vtable pointer is not in the expected section. Use the slow path, which will terminate the process if necessary. */ -- cgit v1.1