On 2/26/2024 7:15 PM, Andreas Rheinhardt wrote:
It is undefined behaviour.
Fixes many failed tests with UBSan and GCC 13 like
"src/libavformat/mov.c:4229:44: runtime error: store to address
0x5572abe20f80 with insufficient space for an object of type 'struct
MOVIndexRange'"
(The line number does not refer to the line where &entry[-1]
is assigned.)
Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@outlook.com>
---
Now switching to next_index_range in order to avoid
having to duplicate the current_index_range == NULL check.
I prefer the first version. mov_fix_index() is called once per track
during init (and then it may not be called depending on user options),
so it's hardly a bottleneck, and next_index_range[-1] is much less clear
and intuitive at a quick glance than current_index_range.
libavformat/mov.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)
diff --git a/libavformat/mov.c b/libavformat/mov.c
index 71e8f7ae8f..d7da19998b 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -4022,7 +4022,7 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
int num_discarded_begin = 0;
int first_non_zero_audio_edit = -1;
int packet_skip_samples = 0;
- MOVIndexRange *current_index_range;
+ MOVIndexRange *next_index_range;
int found_keyframe_after_edit = 0;
int found_non_empty_edit = 0;
@@ -4038,7 +4038,7 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
return;
}
msc->current_index_range = msc->index_ranges;
- current_index_range = msc->index_ranges - 1;
+ next_index_range = msc->index_ranges;
// Clean AVStream from traces of old index
sti->index_entries = NULL;
@@ -4225,11 +4225,11 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
}
// Update the index ranges array
- if (current_index_range < msc->index_ranges || index !=
current_index_range->end) {
- current_index_range++;
- current_index_range->start = index;
+ if (next_index_range == msc->index_ranges || index !=
next_index_range[-1].end) {
+ next_index_range->start = index;
+ next_index_range++;
}
- current_index_range->end = index + 1;
+ next_index_range[-1].end = index + 1;
// Only start incrementing DTS in frame_duration amounts, when we encounter a frame in edit list.
if (edit_list_start_encountered > 0) {
@@ -4289,9 +4289,8 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
av_freep(&frame_duration_buffer);
// Null terminate the index ranges array
- current_index_range++;
- current_index_range->start = 0;
- current_index_range->end = 0;
+ next_index_range->start = 0;
+ next_index_range->end = 0;
msc->current_index = msc->index_ranges[0].start;
}
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