[ Upstream commit 2b6dd600dd72573c23ea180b5b0b2f1813405882 ]
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().
Fixes: fbb0de7950 ("Add udmabuf misc device")
Reported-and-tested-by: syzbot+2c56b725ec547fa9cb29@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20211230142649.23022-1-paskripkin@gmail.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5d50f851dd