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HID: debug: check length before copy_to_user()

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commit 717adfdaf14704fd3ec7fa2c04520c0723247eac upstream.

If our length is greater than the size of the buffer, we
overflow the buffer

Cc: stable@vger.kernel.org
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Daniel Rosenberg 2018-07-02 16:59:37 -07:00 committed by Greg Kroah-Hartman
parent c1d21fe74c
commit 50b4d984f5
1 changed files with 7 additions and 1 deletions
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8
drivers/hid/hid-debug.c
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@ -1154,6 +1154,8 @@ copy_rest:
goto out;
if (list->tail > list->head) {
len = list->tail - list->head;
if (len > count)
len = count;
if (copy_to_user(buffer + ret, &list->hid_debug_buf[list->head], len)) {
ret = -EFAULT;
@ -1163,6 +1165,8 @@ copy_rest:
list->head += len;
} else {
len = HID_DEBUG_BUFSIZE - list->head;
if (len > count)
len = count;
if (copy_to_user(buffer, &list->hid_debug_buf[list->head], len)) {
ret = -EFAULT;
@ -1170,7 +1174,9 @@ copy_rest:
}
list->head = 0;
ret += len;
goto copy_rest;
count -= len;
if (count > 0)
goto copy_rest;
}
}