[FFmpeg-devel] [PATCH] mov demuxer: Check if a key is longer than the atom containing it

[Eugene Zemtsov]

From: Eugene Zemtsov <eugene at chromium.org>

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 at chromium.org>
---
 libavformat/mov.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libavformat/mov.c b/libavformat/mov.c
index 662301bf67..5d2f7fa690 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -5045,15 +5045,18 @@ static int mov_read_keys(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     if (!c->meta_keys)
         return AVERROR(ENOMEM);
 
+    uint32_t bytes_left_in_atom = atom.size;
     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 > bytes_left_in_atom) {
             av_log(c->fc, AV_LOG_ERROR,
                    "The key# %"PRIu32" in meta has invalid size:"
                    "%"PRIu32"\n", i, key_size);
             return AVERROR_INVALIDDATA;
         }
+
+        bytes_left_in_atom -= key_size;
         key_size -= 8;
         if (type != MKTAG('m','d','t','a')) {
             avio_skip(pb, key_size);
-- 
2.44.0.478.gd926399ef9-goog