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* [FFmpeg-devel] [PATCH] mov demuxer: Check if a key is longer than the atom containing it
@ 2024-04-01 23:12 Eugene Zemtsov via ffmpeg-devel
  2024-04-01 23:18 ` James Almer
  0 siblings, 1 reply; 5+ messages in thread
From: Eugene Zemtsov via ffmpeg-devel @ 2024-04-01 23:12 UTC (permalink / raw)
  To: ffmpeg-devel; +Cc: Eugene Zemtsov, eugene

From: Eugene Zemtsov <eugene@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@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

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^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [FFmpeg-devel] [PATCH] mov demuxer: Check if a key is longer than the atom containing it
  2024-04-01 23:12 [FFmpeg-devel] [PATCH] mov demuxer: Check if a key is longer than the atom containing it Eugene Zemtsov via ffmpeg-devel
@ 2024-04-01 23:18 ` James Almer
  2024-04-02  2:28   ` Eugene Zemtsov via ffmpeg-devel
  0 siblings, 1 reply; 5+ messages in thread
From: James Almer @ 2024-04-01 23:18 UTC (permalink / raw)
  To: ffmpeg-devel

On 4/1/2024 8:12 PM, Eugene Zemtsov via ffmpeg-devel wrote:
> From: Eugene Zemtsov <eugene@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@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;

atom is a copy and not used anywhere else in this function, so you can 
just do atom.size -= key_size and check for that above instead.

>           key_size -= 8;
>           if (type != MKTAG('m','d','t','a')) {
>               avio_skip(pb, key_size);
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^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [FFmpeg-devel] [PATCH] mov demuxer: Check if a key is longer than the atom containing it
  2024-04-01 23:18 ` James Almer
@ 2024-04-02  2:28   ` Eugene Zemtsov via ffmpeg-devel
  2024-04-02  2:28     ` Eugene Zemtsov via ffmpeg-devel
  0 siblings, 1 reply; 5+ messages in thread
From: Eugene Zemtsov via ffmpeg-devel @ 2024-04-02  2:28 UTC (permalink / raw)
  To: ffmpeg-devel; +Cc: Eugene Zemtsov, eugene

Thanks for the comments. I got rid of bytes_left_in_atom.

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^ permalink raw reply	[flat|nested] 5+ messages in thread

* [FFmpeg-devel] [PATCH] mov demuxer: Check if a key is longer than the atom containing it
  2024-04-02  2:28   ` Eugene Zemtsov via ffmpeg-devel
@ 2024-04-02  2:28     ` Eugene Zemtsov via ffmpeg-devel
  2024-04-02  3:18       ` James Almer
  0 siblings, 1 reply; 5+ messages in thread
From: Eugene Zemtsov via ffmpeg-devel @ 2024-04-02  2:28 UTC (permalink / raw)
  To: ffmpeg-devel; +Cc: Eugene Zemtsov, eugene

From: Eugene Zemtsov <eugene@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@chromium.org>
---
 libavformat/mov.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libavformat/mov.c b/libavformat/mov.c
index 662301bf67..2d92e7963b 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -5048,12 +5048,13 @@ 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);
-- 
2.44.0.478.gd926399ef9-goog

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ffmpeg-devel@ffmpeg.org
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^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [FFmpeg-devel] [PATCH] mov demuxer: Check if a key is longer than the atom containing it
  2024-04-02  2:28     ` Eugene Zemtsov via ffmpeg-devel
@ 2024-04-02  3:18       ` James Almer
  0 siblings, 0 replies; 5+ messages in thread
From: James Almer @ 2024-04-02  3:18 UTC (permalink / raw)
  To: ffmpeg-devel

On 4/1/2024 11:28 PM, Eugene Zemtsov via ffmpeg-devel wrote:
> From: Eugene Zemtsov <eugene@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@chromium.org>
> ---
>   libavformat/mov.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 662301bf67..2d92e7963b 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -5048,12 +5048,13 @@ 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);

Applied. Thanks.
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^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2024-04-02  3:18 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-04-01 23:12 [FFmpeg-devel] [PATCH] mov demuxer: Check if a key is longer than the atom containing it Eugene Zemtsov via ffmpeg-devel
2024-04-01 23:18 ` James Almer
2024-04-02  2:28   ` Eugene Zemtsov via ffmpeg-devel
2024-04-02  2:28     ` Eugene Zemtsov via ffmpeg-devel
2024-04-02  3:18       ` James Almer

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