[PATCH v5 24/44] kmsan: handle memory sent to/from USB

[Alexander Potapenko <glider@google.com>]

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

v5:
 -- do not export KMSAN hooks that are not called from modules

Link: https://linux-review.googlesource.com/id/Ifa67fb72015d4de14c30e971556f99fc8b2ee506
---
 drivers/usb/core/urb.c |  2 ++
 include/linux/kmsan.h  | 15 +++++++++++++++
 mm/kmsan/hooks.c       | 16 ++++++++++++++++
 3 files changed, 33 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 c6ae00e327e5e..84dddf3aa5f8b 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
 
@@ -227,6 +228,16 @@ 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)
@@ -319,6 +330,10 @@ 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 41b6b41e6183a..58334fa32ff86 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"
@@ -244,6 +245,21 @@ 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);
+}
+
 static void kmsan_handle_dma_page(const void *addr, size_t size,
 				  enum dma_data_direction dir)
 {
-- 
2.37.2.672.g94769d06f0-goog