#syz test

--- a/drivers/usb/mon/mon_bin.c
+++ b/drivers/usb/mon/mon_bin.c
@@ -249,7 +249,11 @@ static unsigned int mon_copy_to_buff(const struct mon_reader_bin *this,
 		 * Copy data and advance pointers.
 		 */
 		buf = this->b_vec[off / CHUNK_SIZE].ptr + off % CHUNK_SIZE;
-		memcpy(buf, from, step_len);
+
+		if (copy_from_kernel_nofault(buf, from, step_len)) {
+			pr_warn("Failed to copy URB transfer buffer content into mon bin.");
+			return -EFAULT;
+		}
 		if ((off += step_len) >= this->b_size) off = 0;
 		from += step_len;
 		length -= step_len;
@@ -413,11 +417,13 @@ static unsigned int mon_bin_get_data(const struct mon_reader_bin *rp,
 
 	*flag = 0;
 	if (urb->num_sgs == 0) {
-		if (urb->transfer_buffer == NULL) {
+		if (
+			urb->transfer_buffer == NULL ||
+			mon_copy_to_buff(rp, offset, urb->transfer_buffer, length) < 0
+		) {
 			*flag = 'Z';
 			return length;
 		}
-		mon_copy_to_buff(rp, offset, urb->transfer_buffer, length);
 		length = 0;
 
 	} else {
@@ -434,6 +440,10 @@ static unsigned int mon_bin_get_data(const struct mon_reader_bin *rp,
 			this_len = min_t(unsigned int, sg->length, length);
 			offset = mon_copy_to_buff(rp, offset, sg_virt(sg),
 					this_len);
+			if (offset < 0) {
+				*flag = 'Z';
+				return length;
+			}
 			length -= this_len;
 		}
 		if (i == 0)

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+86b6d7c8bcc66747c505@syzkaller.appspotmail.com
Tested-by: syzbot+86b6d7c8bcc66747c505@syzkaller.appspotmail.com

Tested on:

commit:         d086c886 Add linux-next specific files for 20250718
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=118af7d4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8a6aa2cafcc62853
dashboard link: https://syzkaller.appspot.com/bug?extid=86b6d7c8bcc66747c505
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15fa638c580000

Note: testing is done by a robot and is best-effort only.