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udmabuf: fix general protection fault in udmabuf_create 

Syzbot reported general protection fault in udmabuf_create. The problem
was in wrong error handling.

In commit 16c243e99d ("udmabuf: Add support for mapping hugepages (v4)")
shmem_read_mapping_page() call was replaced with find_get_page_flags(),
but find_get_page_flags() returns NULL on failure instead PTR_ERR().

Wrong error checking was causing GPF in get_page(), since passed page
was equal to NULL. Fix it by changing if (IS_ER(!hpage)) to if (!hpage)

Reported-by: syzbot+e9cd3122a37c5d6c51e8@syzkaller.appspotmail.com
Fixes: 16c243e99d ("udmabuf: Add support for mapping hugepages (v4)")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20210811175052.21254-1-paskripkin@gmail.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Pavel Skripkin 2021-08-11 20:50:52 +03:00 committed by Gerd Hoffmann
parent 83326a73a1
commit b9770b0b6e
1 changed files with 2 additions and 2 deletions
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4
drivers/dma-buf/udmabuf.c
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@ -227,8 +227,8 @@ static long udmabuf_create(struct miscdevice *device,
if (!hpage) {
hpage = find_get_page_flags(mapping, pgoff,
FGP_ACCESSED);
if (IS_ERR(hpage)) {
ret = PTR_ERR(hpage);
if (!hpage) {
ret = -EINVAL;
goto err;
}
}