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Subject[PATCH] dma-buf: heaps: Fix potential spectre v1 gadget
Date
It appears like nr could be a Spectre v1 gadget as it's supplied by a
user and used as an array index. Prevent the contents
of kernel memory from being leaked to userspace via speculative
execution by using array_index_nospec.

Signed-off-by: Jordy Zomer <jordy@pwning.systems>
---
drivers/dma-buf/dma-heap.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c
index 56bf5ad01ad5..8f5848aa144f 100644
--- a/drivers/dma-buf/dma-heap.c
+++ b/drivers/dma-buf/dma-heap.c
@@ -14,6 +14,7 @@
#include <linux/xarray.h>
#include <linux/list.h>
#include <linux/slab.h>
+#include <linux/nospec.h>
#include <linux/uaccess.h>
#include <linux/syscalls.h>
#include <linux/dma-heap.h>
@@ -135,6 +136,7 @@ static long dma_heap_ioctl(struct file *file, unsigned int ucmd,
if (nr >= ARRAY_SIZE(dma_heap_ioctl_cmds))
return -EINVAL;

+ nr = array_index_nospec(nr, ARRAY_SIZE(dma_heap_ioctl_cmds));
/* Get the kernel ioctl cmd that matches */
kcmd = dma_heap_ioctl_cmds[nr];

--
2.27.0
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