[PATCH 5.4 24/60] udmabuf: add back sanity check

Greg Kroah-Hartman
2022-06-27T11:31:58Z

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