avformat/mov: Check if a key is longer than the atom containing it

Stop reading keys and return AVERROR_INVALIDDATA if key_size
is larger than the amount of space left in the atom.

Bug: https://crbug.com/41496983
Signed-off-by: Eugene Zemtsov <eugene@chromium.org>
Signed-off-by: James Almer <jamrial@gmail.com>
(cherry picked from commit 8a23a145d8)

libavformat/mov.c

@@ -5037,12 +5037,13 @@ static int mov_read_keys(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     for (i = 1; i <= count; ++i) {
         uint32_t key_size = avio_rb32(pb);
         uint32_t type = avio_rl32(pb);
-        if (key_size < 8) {
+        if (key_size < 8 || key_size > atom.size) {
             av_log(c->fc, AV_LOG_ERROR,
                    "The key# %"PRIu32" in meta has invalid size:"
                    "%"PRIu32"\n", i, key_size);
             return AVERROR_INVALIDDATA;
         }
+        atom.size -= key_size;
         key_size -= 8;
         if (type != MKTAG('m','d','t','a')) {
             avio_skip(pb, key_size);