Andrey used the syzkaller fuzzer to find an out-of-bounds memory
access in usb_get_bos_descriptor(). The code wasn't checking that the
next usb_dev_cap_header structure could fit into the remaining buffer
space.
This patch fixes the error and also reduces the bNumDeviceCaps field
in the header to match the actual number of capabilities found, in
cases where there are fewer than expected.
Signed-off-by: Alan Stern <st...@rowland.harvard.edu>
Tested-by: Andrey Konovalov <andreyk...@google.com>
CC: <sta...@vger.kernel.org>
---
[as1851]
drivers/usb/core/config.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
Index: usb-4.x/drivers/usb/core/config.c
===================================================================
--- usb-4.x.orig/drivers/usb/core/config.c
+++ usb-4.x/drivers/usb/core/config.c
@@ -952,10 +952,12 @@ int usb_get_bos_descriptor(struct usb_de
for (i = 0; i < num; i++) {
buffer += length;
cap = (struct usb_dev_cap_header *)buffer;
- length = cap->bLength;
- if (total_len < length)
+ if (total_len < sizeof(*cap) || total_len < cap->bLength) {
+ dev->bos->desc->bNumDeviceCaps = i;
break;
+ }
+ length = cap->bLength;
total_len -= length;
if (cap->bDescriptorType != USB_DT_DEVICE_CAPABILITY) {
--
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