[Linaro-mm-sig] Re: [PATCH] udmabuf: validate ubuf->pagecount

On Thu, Dec 30, 2021 at 05:26:49PM +0300, Pavel Skripkin wrote:

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 paskripkin@gmail.com

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Pushed to drm-misc-next.

thanks, Gerd