Copied from https://hg.mozilla.org/releases/mozilla-esr38/raw-rev/88f1eb2c3f4b

# HG changeset patch
# User Timothy Nikkel <tnikkel@gmail.com>
# Date 1457637807 21600
# Node ID 88f1eb2c3f4b4b57365ed88223cf8adc2bec4610
# Parent  bf34b97757b334af1f9f53b9b59e0b6902e7ed6f
Bug 1187420. r=drc r=jmuizelaar a=sylvestre

MozReview-Commit-ID: Hh0Khqfj8Bf

diff --git a/media/libjpeg/jstdhuff.c b/media/libjpeg/jstdhuff.c
--- a/media/libjpeg/jstdhuff.c
+++ b/media/libjpeg/jstdhuff.c
@@ -36,16 +36,17 @@ add_huff_table (j_common_ptr cinfo,
    */
   nsymbols = 0;
   for (len = 1; len <= 16; len++)
     nsymbols += bits[len];
   if (nsymbols < 1 || nsymbols > 256)
     ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
 
   MEMCOPY((*htblptr)->huffval, val, nsymbols * sizeof(UINT8));
+  MEMZERO(&((*htblptr)->huffval[nsymbols]), (256 - nsymbols) * sizeof(UINT8));
 
   /* Initialize sent_table FALSE so table will be written to JPEG file. */
   (*htblptr)->sent_table = FALSE;
 }
 
 
 LOCAL(void)
 std_huff_tables (j_common_ptr cinfo)