From: Gerd Hoffmann <kraxel@redhat.com>
Date: Mon, 20 Jun 2022 07:15:47 +0000 (+0200)
Subject: udmabuf: add back sanity check
X-Git-Tag: v6.1-rc5~1032
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=05b252cccb2e5c3f56119d25de684b4f810ba40a;p=platform%2Fkernel%2Flinux-starfive.git

udmabuf: add back sanity check

Check vm_fault->pgoff before using it.  When we removed the warning, we
also removed the check.

Fixes: 7b26e4e2119d ("udmabuf: drop WARN_ON() check.")
Reported-by: zdi-disclosures@trendmicro.com
Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index e733068..9631f2f 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -32,8 +32,11 @@ static vm_fault_t udmabuf_vm_fault(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct udmabuf *ubuf = vma->vm_private_data;
+	pgoff_t pgoff = vmf->pgoff;
 
-	vmf->page = ubuf->pages[vmf->pgoff];
+	if (pgoff >= ubuf->pagecount)
+		return VM_FAULT_SIGBUS;
+	vmf->page = ubuf->pages[pgoff];
 	get_page(vmf->page);
 	return 0;
 }