powerpc/pseries/hvconsole: Fix stack overread via udbg

[mirror_ubuntu-bionic-kernel.git] / arch / powerpc / platforms / pseries / hvconsole.c

diff --git a/arch/powerpc/platforms/pseries/hvconsole.c b/arch/powerpc/platforms/pseries/hvconsole.c
index 74da18de853af670f911acc800e50d076bff4f8c..73ec15cd27080f256cd86ac57f04f48550686603 100644 (file)
--- a/arch/powerpc/platforms/pseries/hvconsole.c
+++ b/arch/powerpc/platforms/pseries/hvconsole.c
@@ -62,7 +62,7 @@ EXPORT_SYMBOL(hvc_get_chars);
  * @vtermno: The vtermno or unit_address of the adapter from which the data
  *     originated.
  * @buf: The character buffer that contains the character data to send to
- *     firmware.
+ *     firmware. Must be at least 16 bytes, even if count is less than 16.
  * @count: Send this number of characters.
  */
 int hvc_put_chars(uint32_t vtermno, const char *buf, int count)