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udmabuf: validate ubuf->pagecount

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[ 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>
This commit is contained in:
Pavel Skripkin 2021-12-30 17:26:49 +03:00 committed by Greg Kroah-Hartman
parent 2cf7d537d3
commit 5d50f851dd
1 changed files with 4 additions and 0 deletions

4
drivers/dma-buf/udmabuf.c
View File

@ -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) {