[FFmpeg-devel] [PATCH] avformat/subfile: clip seek offset

[FFmpeg-devel] [PATCH] avformat/subfile: clip seek offset

[Kacper Michajłow]

Fixes: signed integer overflow: 9223372036854737920 + 1649410 cannot be
represented in type 'int64_t'

Fixes OSS-Fuzz: 410100610

Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
---
 libavformat/subfile.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/libavformat/subfile.c b/libavformat/subfile.c
index be48ef72ef..b8c6ce0eef 100644
--- a/libavformat/subfile.c
+++ b/libavformat/subfile.c
@@ -128,13 +128,13 @@ static int64_t subfile_seek(URLContext *h, int64_t pos, int whence)
     case AVSEEK_SIZE:
         return end - c->start;
     case SEEK_SET:
-        new_pos = c->start + pos;
+        new_pos = c->start + av_clip(pos, 0, end - c->start);
         break;
     case SEEK_CUR:
-        new_pos = c->pos + pos;
+        new_pos = c->pos + av_clip(pos, -(c->pos - c->start), end - c->pos);
         break;
     case SEEK_END:
-        new_pos = end + pos;
+        new_pos = end + av_clip(pos, -(end - c->start), 0);
         break;
     default:
         av_assert0(0);
-- 
2.47.2

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Re: [FFmpeg-devel] [PATCH] avformat/subfile: clip seek offset

[Kacper Michajlow]

On Fri, 11 Jul 2025 at 21:49, Kacper Michajłow <kasper93@gmail.com> wrote:

> Fixes: signed integer overflow: 9223372036854737920 + 1649410 cannot be
> represented in type 'int64_t'
>
> Fixes OSS-Fuzz: 410100610
>
> Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
> ---
>  libavformat/subfile.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/libavformat/subfile.c b/libavformat/subfile.c
> index be48ef72ef..b8c6ce0eef 100644
> --- a/libavformat/subfile.c
> +++ b/libavformat/subfile.c
> @@ -128,13 +128,13 @@ static int64_t subfile_seek(URLContext *h, int64_t
> pos, int whence)
>      case AVSEEK_SIZE:
>          return end - c->start;
>      case SEEK_SET:
> -        new_pos = c->start + pos;
> +        new_pos = c->start + av_clip(pos, 0, end - c->start);
>          break;
>      case SEEK_CUR:
> -        new_pos = c->pos + pos;
> +        new_pos = c->pos + av_clip(pos, -(c->pos - c->start), end -
> c->pos);
>          break;
>      case SEEK_END:
> -        new_pos = end + pos;
> +        new_pos = end + av_clip(pos, -(end - c->start), 0);
>          break;
>      default:
>          av_assert0(0);
> --
> 2.47.2
>
>
Will apply later if there is no objection.

- Kacper
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Re: [FFmpeg-devel] [PATCH] avformat/subfile: clip seek offset

[Michael Niedermayer]

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On Fri, Jul 11, 2025 at 09:49:29PM +0200, Kacper Michajłow wrote:
> Fixes: signed integer overflow: 9223372036854737920 + 1649410 cannot be
> represented in type 'int64_t'
> 
> Fixes OSS-Fuzz: 410100610
> 
> Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
> ---
>  libavformat/subfile.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/libavformat/subfile.c b/libavformat/subfile.c
> index be48ef72ef..b8c6ce0eef 100644
> --- a/libavformat/subfile.c
> +++ b/libavformat/subfile.c
> @@ -128,13 +128,13 @@ static int64_t subfile_seek(URLContext *h, int64_t pos, int whence)
>      case AVSEEK_SIZE:
>          return end - c->start;
>      case SEEK_SET:
> -        new_pos = c->start + pos;
> +        new_pos = c->start + av_clip(pos, 0, end - c->start);
>          break;
>      case SEEK_CUR:
> -        new_pos = c->pos + pos;
> +        new_pos = c->pos + av_clip(pos, -(c->pos - c->start), end - c->pos);
>          break;
>      case SEEK_END:
> -        new_pos = end + pos;
> +        new_pos = end + av_clip(pos, -(end - c->start), 0);
>          break;
>      default:
>          av_assert0(0);

regression fix for this is here:
https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20055

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

During times of universal deceit, telling the truth becomes a
revolutionary act. -- George Orwell

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Re: [FFmpeg-devel] [PATCH] avformat/subfile: clip seek offset

[Nicolas George]

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Michael Niedermayer (HE12025-07-29):
> regression fix for this is here:
> https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20055

I see no commit message.

I see removing opening braces without removing them.

(see attached screenshot; maybe it looks better for others)

As is: rejected and revert the previous patch.

Regards,

-- 
  Nicolas George

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Re: [FFmpeg-devel] [PATCH] avformat/subfile: clip seek offset

[Alexander Strasser via ffmpeg-devel]

Hi Nicolas!

Am 29. Juli 2025 10:55:15 MESZ schrieb Nicolas George <george@nsup.org>:
>Michael Niedermayer (HE12025-07-29):
>> regression fix for this is here:
>> https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20055
>
>I see no commit message.
>
>I see removing opening braces without removing them.
>
>(see attached screenshot; maybe it looks better for others)

You are looking at the overview with latest events for that PR.

To see the the individual commits select
that view at the top. Or if you want to see
the combined diff, click on changes one
further to the right.


Best regards,
  Alexander


>As is: rejected and revert the previous patch.
>
>Regards,
>
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