CVE-2021-47649

In the Linux kernel, the following vulnerability has been resolved: udmabuf: validate ubuf->pagecount Syzbot has reported GPF in sg_alloc_append_table_from_pages(). The problem was in ubuf->pages == ZERO_PTR. ubuf->pagecount is calculated from arguments passed from user-space. If user creates udmabuf with list.size == 0 then ubuf->pagecount will be also equal to zero; it causes kmalloc_array() to return ZERO_PTR. Fix it by validating ubuf->pagecount before passing it to kmalloc_array().

• linux linux kernel (>= 4.20 < 5.4.189) • linux linux kernel (>= 5.5 < 5.10.110) • linux linux kernel (>= 5.11 < 5.15.33) • linux linux kernel (>= 5.16 < 5.16.19) • linux linux kernel (>= 5.17 < 5.17.2)