From a67b2913e291efbbfbfb86a614667628572584f9 Mon Sep 17 00:00:00 2001 From: Pavel Skripkin Date: Thu, 30 Dec 2021 17:26:49 +0300 Subject: [PATCH] udmabuf: validate ubuf->pagecount BugLink: https://bugs.launchpad.net/bugs/1971497 [ 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: fbb0de795078 ("Add udmabuf misc device") Reported-and-tested-by: syzbot+2c56b725ec547fa9cb29@syzkaller.appspotmail.com Signed-off-by: Pavel Skripkin Link: http://patchwork.freedesktop.org/patch/msgid/20211230142649.23022-1-paskripkin@gmail.com Signed-off-by: Gerd Hoffmann Signed-off-by: Sasha Levin Signed-off-by: Kamal Mostafa Signed-off-by: Stefan Bader --- drivers/dma-buf/udmabuf.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c index 9635897458a0..e553c6a937f6 100644 --- a/drivers/dma-buf/udmabuf.c +++ b/drivers/dma-buf/udmabuf.c @@ -145,6 +145,10 @@ static long udmabuf_create(const struct udmabuf_create_list *head, if (ubuf->pagecount > pglimit) goto err; } + + if (!ubuf->pagecount) + goto err; + ubuf->pages = kmalloc_array(ubuf->pagecount, sizeof(*ubuf->pages), GFP_KERNEL); if (!ubuf->pages) { -- 2.39.5