Commit 5d50f851 authored Dec 30, 2021 by Pavel Skripkin Committed by Greg Kroah-Hartman Apr 15, 2022

udmabuf: validate ubuf->pagecount



[ 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: fbb0de79 ("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>

parent 2cf7d537

drivers/dma-buf/udmabuf.c

+4 −0

Original line number	Original line	Diff line number	Diff line
	@@ -145,6 +145,10 @@ static long udmabuf_create(const struct udmabuf_create_list *head,
	if (ubuf->pagecount > pglimit)		if (ubuf->pagecount > pglimit)
	goto err;		goto err;
	}		}

			if (!ubuf->pagecount)
			goto err;

	ubuf->pages = kmalloc_array(ubuf->pagecount, sizeof(*ubuf->pages),		ubuf->pages = kmalloc_array(ubuf->pagecount, sizeof(*ubuf->pages),
	GFP_KERNEL);		GFP_KERNEL);
	if (!ubuf->pages) {		if (!ubuf->pages) {