On 8/7/2021 9:38 PM, Soft Works wrote:
-----Original Message-----
From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> On Behalf Of
Carl Eugen Hoyos
Sent: Sunday, 8 August 2021 01:58
To: FFmpeg development discussions and patches <ffmpeg-
de...@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH v2] libavformat/asfdec: Fix regression
bug when reading image attachments
Am So., 8. Aug. 2021 um 01:53 Uhr schrieb Soft Works
<softwo...@hotmail.com>:
Commit c8140fe7324f264faacf7395b27e12531d1f13f7 had introduced a
check for value_len > UINT16_MAX.
As a consequence, attached images of sizes larger than UINT16_MAX could
no longer be read.
Signed-off-by: softworkz <softwo...@hotmail.com>
---
v2: Fix without changing variable type libavformat/asfdec_f.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libavformat/asfdec_f.c b/libavformat/asfdec_f.c index
ff6ddfb967..b9f3918495 100644
--- a/libavformat/asfdec_f.c
+++ b/libavformat/asfdec_f.c
@@ -614,7 +614,7 @@ static int asf_read_metadata(AVFormatContext *s,
int64_t size)
value_type = avio_rl16(pb); /* value_type */
value_len = avio_rl32(pb);
- if (value_len < 0 || value_len > UINT16_MAX)
+ if (value_len < 0)
return AVERROR_INVALIDDATA;
I may misread the code but it appears to me that an assert can be triggered
now, no?
Right, for these 11 discrete size values only, though:
2147483647, 2147483646, 2147483645, 2147483644, 2147483643,
2147483642, 2147483641, 2147483640, 2147483639, 2147483638
2147483636
A chance of 11 in 4 Billions :-)
len < (INT_MAX - LEN) / 2 is more than half the range of an int.
TBH, I don't understand this assert. When the attachment is too large
to handle, we should rather log a warning and goto finish instead IMO.
The assert is to ensure get_tag() is not called with out of range
values, so the relevant checks should happen before the call.
softworkz
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