[PATCH v4 24/45] kmsan: handle memory sent to/from USB

Alexander Potapenko
2022-07-01T14:27:21Z

Depending on the value of is_out kmsan_handle_urb() KMSAN either
marks the data copied to the kernel from a USB device as initialized,
or checks the data sent to the device for being initialized.

Signed-off-by: Alexander Potapenko <glider@google.com>

---
v2:
-- move kmsan_handle_urb() implementation to this patch

Link: https://linux-review.googlesource.com/id/Ifa67fb72015d4de14c30e971556f99fc8b2ee506
---
drivers/usb/core/urb.c | 2 ++
include/linux/kmsan.h | 15 +++++++++++++++
mm/kmsan/hooks.c | 17 +++++++++++++++++
3 files changed, 34 insertions(+)

diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index 33d62d7e3929f..1fe3f23205624 100644
--- a/drivers/usb/core/urb.c
+++ b/drivers/usb/core/urb.c
@@ -8,6 +8,7 @@
#include <linux/bitops.h>
#include <linux/slab.h>
#include <linux/log2.h>
+#include <linux/kmsan-checks.h>
#include <linux/usb.h>
#include <linux/wait.h>
#include <linux/usb/hcd.h>
@@ -426,6 +427,7 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
URB_SETUP_MAP_SINGLE | URB_SETUP_MAP_LOCAL |
URB_DMA_SG_COMBINED);
urb->transfer_flags |= (is_out ? URB_DIR_OUT : URB_DIR_IN);
+ kmsan_handle_urb(urb, is_out);

if (xfertype != USB_ENDPOINT_XFER_CONTROL &&
dev->state < USB_STATE_CONFIGURED)
diff --git a/include/linux/kmsan.h b/include/linux/kmsan.h
index 55fe673ee1e84..e8b5c306c4aa1 100644
--- a/include/linux/kmsan.h
+++ b/include/linux/kmsan.h
@@ -19,6 +19,7 @@ struct page;
struct kmem_cache;
struct task_struct;
struct scatterlist;
+struct urb;

#ifdef CONFIG_KMSAN

@@ -235,6 +236,16 @@ void kmsan_handle_dma(struct page *page, size_t offset, size_t size,
void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
enum dma_data_direction dir);

+/**
+ * kmsan_handle_urb() - Handle a USB data transfer.
+ * @urb: struct urb pointer.
+ * @is_out: data transfer direction (true means output to hardware).
+ *
+ * If @is_out is true, KMSAN checks the transfer buffer of @urb. Otherwise,
+ * KMSAN initializes the transfer buffer.
+ */
+void kmsan_handle_urb(const struct urb *urb, bool is_out);
+
#else

static inline void kmsan_init_shadow(void)
@@ -327,6 +338,10 @@ static inline void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
{
}

+static inline void kmsan_handle_urb(const struct urb *urb, bool is_out)
+{
+}
+
#endif

#endif /* _LINUX_KMSAN_H */
diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c
index 8a6947a2a2f22..9aecbf2825837 100644
--- a/mm/kmsan/hooks.c
+++ b/mm/kmsan/hooks.c
@@ -17,6 +17,7 @@
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
+#include <linux/usb.h>

#include "../internal.h"
#include "../slab.h"
@@ -252,6 +253,22 @@ void kmsan_copy_to_user(void __user *to, const void *from, size_t to_copy,
}
EXPORT_SYMBOL(kmsan_copy_to_user);

+/* Helper function to check an URB. */
+void kmsan_handle_urb(const struct urb *urb, bool is_out)
+{
+ if (!urb)
+ return;
+ if (is_out)
+ kmsan_internal_check_memory(urb->transfer_buffer,
+ urb->transfer_buffer_length,
+ /*user_addr*/ 0, REASON_SUBMIT_URB);
+ else
+ kmsan_internal_unpoison_memory(urb->transfer_buffer,
+ urb->transfer_buffer_length,
+ /*checked*/ false);
+}
+EXPORT_SYMBOL(kmsan_handle_urb);
+
static void kmsan_handle_dma_page(const void *addr, size_t size,
enum dma_data_direction dir)
{
--
2.37.0.rc0.161.g10f37bed90-goog