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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, zdi-disclosures@trendmicro.com,
        Linus Torvalds <torvalds@linuxfoundation.org>,
        Gerd Hoffmann <kraxel@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 24/60] udmabuf: add back sanity check
Date:   Mon, 27 Jun 2022 13:21:35 +0200
Message-Id: <20220627111928.376754235@linuxfoundation.org>
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From: Gerd Hoffmann <kraxel@redhat.com>

[ Upstream commit 05b252cccb2e5c3f56119d25de684b4f810ba40a ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/dma-buf/udmabuf.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index e553c6a937f6..c6e9b7bd7618 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -24,8 +24,11 @@ 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;
 }
-- 
2.35.1