diff mbox

[FFmpeg-devel] libavutil/encryption_info: Allow multiple init info.

Message ID CAO7y9i-vUp9CpK7F_uD5u4tNdVEVmW0fjFUxqakbWX5od7v6aQ@mail.gmail.com
State Superseded
Headers show

Commit Message

Jacob Trimble May 31, 2018, 4:40 p.m. UTC 
On Fri, May 25, 2018 at 6:13 PM Michael Niedermayer
<michael@niedermayer.cc> wrote:
>
> [...]
>
> > Added fix for issue found by Chrome's ClusterFuzz (http://crbug.com/846662).
>
> this belongs in a seperate patch unless its a bug specific to the code added
> with this patch
>

Ok.  Now this patch depends on
http://ffmpeg.org/pipermail/ffmpeg-devel/2018-May/230782.html.

> [...]
>
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> I have often repented speaking, but never of holding my tongue.
> -- Xenocrates
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel

Comments

Jacob Trimble June 1, 2018, 12:50 a.m. UTC | #1 
On Thu, May 31, 2018 at 9:40 AM Jacob Trimble <modmaker@google.com> wrote:
>
> On Fri, May 25, 2018 at 6:13 PM Michael Niedermayer
> <michael@niedermayer.cc> wrote:
> >
> > [...]
> >
> > > Added fix for issue found by Chrome's ClusterFuzz (http://crbug.com/846662).
> >
> > this belongs in a seperate patch unless its a bug specific to the code added
> > with this patch
> >
>
> Ok.  Now this patch depends on
> http://ffmpeg.org/pipermail/ffmpeg-devel/2018-May/230782.html.
>

Noticed some bugs when integrating it.

> > [...]
> >
> > --
> > Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> >
> > I have often repented speaking, but never of holding my tongue.
> > -- Xenocrates
> > _______________________________________________
> > ffmpeg-devel mailing list
> > ffmpeg-devel@ffmpeg.org
> > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
Jacob Trimble June 7, 2018, 6:51 p.m. UTC | #2 
On Thu, May 31, 2018 at 5:50 PM Jacob Trimble <modmaker@google.com> wrote:
>
> On Thu, May 31, 2018 at 9:40 AM Jacob Trimble <modmaker@google.com> wrote:
> >
> > On Fri, May 25, 2018 at 6:13 PM Michael Niedermayer
> > <michael@niedermayer.cc> wrote:
> > >
> > > [...]
> > >
> > > > Added fix for issue found by Chrome's ClusterFuzz (http://crbug.com/846662).
> > >
> > > this belongs in a seperate patch unless its a bug specific to the code added
> > > with this patch
> > >
> >
> > Ok.  Now this patch depends on
> > http://ffmpeg.org/pipermail/ffmpeg-devel/2018-May/230782.html.
> >
>
> Noticed some bugs when integrating it.
>
> > > [...]
> > >
> > > --
> > > Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> > >
> > > I have often repented speaking, but never of holding my tongue.
> > > -- Xenocrates
> > > _______________________________________________
> > > ffmpeg-devel mailing list
> > > ffmpeg-devel@ffmpeg.org
> > > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel

Removed controversial NULL checks.  This patch no longer depends on anything.
Jacob Trimble June 14, 2018, 4:44 p.m. UTC | #3 
On Thu, Jun 7, 2018 at 11:51 AM Jacob Trimble <modmaker@google.com> wrote:
>
> On Thu, May 31, 2018 at 5:50 PM Jacob Trimble <modmaker@google.com> wrote:
> >
> > On Thu, May 31, 2018 at 9:40 AM Jacob Trimble <modmaker@google.com> wrote:
> > >
> > > On Fri, May 25, 2018 at 6:13 PM Michael Niedermayer
> > > <michael@niedermayer.cc> wrote:
> > > >
> > > > [...]
> > > >
> > > > > Added fix for issue found by Chrome's ClusterFuzz (http://crbug.com/846662).
> > > >
> > > > this belongs in a seperate patch unless its a bug specific to the code added
> > > > with this patch
> > > >
> > >
> > > Ok.  Now this patch depends on
> > > http://ffmpeg.org/pipermail/ffmpeg-devel/2018-May/230782.html.
> > >
> >
> > Noticed some bugs when integrating it.
> >
> > > > [...]
> > > >
> > > > --
> > > > Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> > > >
> > > > I have often repented speaking, but never of holding my tongue.
> > > > -- Xenocrates
> > > > _______________________________________________
> > > > ffmpeg-devel mailing list
> > > > ffmpeg-devel@ffmpeg.org
> > > > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> Removed controversial NULL checks.  This patch no longer depends on anything.

Ping.
Jacob Trimble June 20, 2018, 4:48 p.m. UTC | #4 
On Thu, Jun 14, 2018 at 9:44 AM Jacob Trimble <modmaker@google.com> wrote:
>
> On Thu, Jun 7, 2018 at 11:51 AM Jacob Trimble <modmaker@google.com> wrote:
> >
> > On Thu, May 31, 2018 at 5:50 PM Jacob Trimble <modmaker@google.com> wrote:
> > >
> > > On Thu, May 31, 2018 at 9:40 AM Jacob Trimble <modmaker@google.com> wrote:
> > > >
> > > > On Fri, May 25, 2018 at 6:13 PM Michael Niedermayer
> > > > <michael@niedermayer.cc> wrote:
> > > > >
> > > > > [...]
> > > > >
> > > > > > Added fix for issue found by Chrome's ClusterFuzz (http://crbug.com/846662).
> > > > >
> > > > > this belongs in a seperate patch unless its a bug specific to the code added
> > > > > with this patch
> > > > >
> > > >
> > > > Ok.  Now this patch depends on
> > > > http://ffmpeg.org/pipermail/ffmpeg-devel/2018-May/230782.html.
> > > >
> > >
> > > Noticed some bugs when integrating it.
> > >
> > > > > [...]
> > > > >
> > > > > --
> > > > > Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> > > > >
> > > > > I have often repented speaking, but never of holding my tongue.
> > > > > -- Xenocrates
> > > > > _______________________________________________
> > > > > ffmpeg-devel mailing list
> > > > > ffmpeg-devel@ffmpeg.org
> > > > > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> >
> > Removed controversial NULL checks.  This patch no longer depends on anything.
>
> Ping.

Ping.
Michael Niedermayer June 21, 2018, 4:47 p.m. UTC | #5 
On Thu, Jun 07, 2018 at 11:51:30AM -0700, Jacob Trimble wrote:
> On Thu, May 31, 2018 at 5:50 PM Jacob Trimble <modmaker@google.com> wrote:
> >
> > On Thu, May 31, 2018 at 9:40 AM Jacob Trimble <modmaker@google.com> wrote:
> > >
> > > On Fri, May 25, 2018 at 6:13 PM Michael Niedermayer
> > > <michael@niedermayer.cc> wrote:
> > > >
> > > > [...]
> > > >
> > > > > Added fix for issue found by Chrome's ClusterFuzz (http://crbug.com/846662).
> > > >
> > > > this belongs in a seperate patch unless its a bug specific to the code added
> > > > with this patch
> > > >
> > >
> > > Ok.  Now this patch depends on
> > > http://ffmpeg.org/pipermail/ffmpeg-devel/2018-May/230782.html.
> > >
> >
> > Noticed some bugs when integrating it.
> >
> > > > [...]
> > > >
> > > > --
> > > > Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> > > >
> > > > I have often repented speaking, but never of holding my tongue.
> > > > -- Xenocrates
> > > > _______________________________________________
> > > > ffmpeg-devel mailing list
> > > > ffmpeg-devel@ffmpeg.org
> > > > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> 
> Removed controversial NULL checks.  This patch no longer depends on anything.

>  encryption_info.c |  140 ++++++++++++++++++++++++++++++++++++------------------
>  encryption_info.h |    5 +
>  2 files changed, 100 insertions(+), 45 deletions(-)
> cc25918cb63c4ac75f0b693472b51590c1a74052  0001-libavutil-encryption_info-Allow-multiple-init-info-v7.patch
> From 0c4c33f26ba4204a775709cdd6367dd1ea4bd024 Mon Sep 17 00:00:00 2001
> From: Jacob Trimble <modmaker@google.com>
> Date: Mon, 23 Apr 2018 10:33:58 -0700
> Subject: [PATCH] libavutil/encryption_info: Allow multiple init info.
> 
> It is possible for there to be multiple encryption init info structure.
> For example, to support multiple key systems or in key rotation.  This
> changes the AVEncryptionInitInfo struct to be a linked list so there
> can be multiple structs without breaking ABI.
> 
> Signed-off-by: Jacob Trimble <modmaker@google.com>
> ---
>  libavutil/encryption_info.c | 140 ++++++++++++++++++++++++------------
>  libavutil/encryption_info.h |   5 ++
>  2 files changed, 100 insertions(+), 45 deletions(-)
> 
> diff --git a/libavutil/encryption_info.c b/libavutil/encryption_info.c
> index 20a752d6b4..1072d2795b 100644
> --- a/libavutil/encryption_info.c
> +++ b/libavutil/encryption_info.c
> @@ -160,13 +160,16 @@ uint8_t *av_encryption_info_add_side_data(const AVEncryptionInfo *info, size_t *
>  }
>  
>  // The format of the AVEncryptionInitInfo side data:
> -// u32be system_id_size
> -// u32be num_key_ids
> -// u32be key_id_size
> -// u32be data_size
> -// u8[system_id_size] system_id
> -// u8[key_id_size][num_key_id] key_ids
> -// u8[data_size] data
> +// u32be init_info_count
> +// {
> +//   u32be system_id_size
> +//   u32be num_key_ids
> +//   u32be key_id_size
> +//   u32be data_size
> +//   u8[system_id_size] system_id
> +//   u8[key_id_size][num_key_id] key_ids
> +//   u8[data_size] data
> +// }[init_info_count]
>  
>  #define FF_ENCRYPTION_INIT_INFO_EXTRA 16
>  
> @@ -215,6 +218,7 @@ void av_encryption_init_info_free(AVEncryptionInitInfo *info)
>          for (i = 0; i < info->num_key_ids; i++) {
>              av_free(info->key_ids[i]);
>          }
> +        av_encryption_init_info_free(info->next);
>          av_free(info->system_id);
>          av_free(info->key_ids);
>          av_free(info->data);
> @@ -225,71 +229,117 @@ void av_encryption_init_info_free(AVEncryptionInitInfo *info)
>  AVEncryptionInitInfo *av_encryption_init_info_get_side_data(
>      const uint8_t *side_data, size_t side_data_size)
>  {
> -    AVEncryptionInitInfo *info;
> -    uint64_t system_id_size, num_key_ids, key_id_size, data_size, i;
> +    // |ret| tracks the front of the list, |info| tracks the back.
> +    AVEncryptionInitInfo *ret = NULL, *info, *temp_info;
> +    uint64_t system_id_size, num_key_ids, key_id_size, data_size, i, j;
> +    uint64_t init_info_count;
>  
> -    if (!side_data || side_data_size < FF_ENCRYPTION_INIT_INFO_EXTRA)
> +    if (!side_data || side_data_size < 4)
>          return NULL;
>  
> -    system_id_size = AV_RB32(side_data);
> -    num_key_ids = AV_RB32(side_data + 4);
> -    key_id_size = AV_RB32(side_data + 8);
> -    data_size = AV_RB32(side_data + 12);
> +    init_info_count = AV_RB32(side_data);
> +    side_data += 4;
> +    side_data_size -= 4;
> +    for (i = 0; i < init_info_count; i++) {
> +        if (side_data_size < FF_ENCRYPTION_INIT_INFO_EXTRA) {
> +            av_encryption_init_info_free(ret);
> +            return NULL;
> +        }
>  
> -    // UINT32_MAX + UINT32_MAX + UINT32_MAX * UINT32_MAX == UINT64_MAX
> -    if (side_data_size - FF_ENCRYPTION_INIT_INFO_EXTRA < system_id_size + data_size + num_key_ids * key_id_size)
> -        return NULL;
> +        system_id_size = AV_RB32(side_data);
> +        num_key_ids = AV_RB32(side_data + 4);
> +        key_id_size = AV_RB32(side_data + 8);
> +        data_size = AV_RB32(side_data + 12);
>  
> -    info = av_encryption_init_info_alloc(system_id_size, num_key_ids, key_id_size, data_size);
> -    if (!info)
> -        return NULL;
> +        // UINT32_MAX + UINT32_MAX + UINT32_MAX * UINT32_MAX == UINT64_MAX
> +        if (side_data_size - FF_ENCRYPTION_INIT_INFO_EXTRA < system_id_size + data_size + num_key_ids * key_id_size) {
> +            av_encryption_init_info_free(ret);
> +            return NULL;
> +        }
> +        side_data += FF_ENCRYPTION_INIT_INFO_EXTRA;
> +        side_data_size -= FF_ENCRYPTION_INIT_INFO_EXTRA;
>  
> -    memcpy(info->system_id, side_data + 16, system_id_size);
> -    side_data += system_id_size + 16;
> -    for (i = 0; i < num_key_ids; i++) {
> -      memcpy(info->key_ids[i], side_data, key_id_size);
> -      side_data += key_id_size;
> +        temp_info = av_encryption_init_info_alloc(system_id_size, num_key_ids, key_id_size, data_size);
> +        if (!temp_info) {
> +            av_encryption_init_info_free(ret);
> +            return NULL;
> +        }
> +        if (i == 0) {
> +            info = ret = temp_info;
> +        } else {
> +            info->next = temp_info;
> +            info = temp_info;
> +        }
> +
> +        memcpy(info->system_id, side_data, system_id_size);
> +        side_data += system_id_size;
> +        side_data_size -= system_id_size;
> +        for (j = 0; j < num_key_ids; j++) {
> +            memcpy(info->key_ids[j], side_data, key_id_size);
> +            side_data += key_id_size;
> +            side_data_size -= key_id_size;
> +        }
> +        memcpy(info->data, side_data, data_size);
> +        side_data += data_size;
> +        side_data_size -= data_size;
>      }
> -    memcpy(info->data, side_data, data_size);
>  
> -    return info;
> +    return ret;
>  }
>  
>  uint8_t *av_encryption_init_info_add_side_data(const AVEncryptionInitInfo *info, size_t *side_data_size)
>  {
> +    const AVEncryptionInitInfo *cur_info;
>      uint8_t *buffer, *cur_buffer;
> -    uint32_t i, max_size;
> +    uint32_t i, init_info_count;
>  
>      if (UINT32_MAX - FF_ENCRYPTION_INIT_INFO_EXTRA < info->system_id_size ||
>          UINT32_MAX - FF_ENCRYPTION_INIT_INFO_EXTRA - info->system_id_size < info->data_size) {
>          return NULL;
>      }
>  
> -    if (info->num_key_ids) {
> -        max_size = UINT32_MAX - FF_ENCRYPTION_INIT_INFO_EXTRA - info->system_id_size - info->data_size;
> -        if (max_size / info->num_key_ids < info->key_id_size)
> +    *side_data_size = 4;
> +    init_info_count = 0;
> +    for (cur_info = info; cur_info; cur_info = cur_info->next) {

> +        if (UINT32_MAX == init_info_count ||
> +            UINT32_MAX - *side_data_size < FF_ENCRYPTION_INIT_INFO_EXTRA ||
> +            UINT32_MAX - *side_data_size - FF_ENCRYPTION_INIT_INFO_EXTRA < info->system_id_size ||
> +            UINT32_MAX - *side_data_size - FF_ENCRYPTION_INIT_INFO_EXTRA - info->system_id_size < info->data_size) {
>              return NULL;
> +        }

you can simplify this with (u)int64_t

[...]
diff mbox

Patch

From 468958a26c1df8f599925038518ca4dae90de0f7 Mon Sep 17 00:00:00 2001
From: Jacob Trimble <modmaker@google.com>
Date: Mon, 23 Apr 2018 10:33:58 -0700
Subject: [PATCH] libavutil/encryption_info: Allow multiple init info.

It is possible for there to be multiple encryption init info structure.
For example, to support multiple key systems or in key rotation.  This
changes the AVEncryptionInitInfo struct to be a linked list so there
can be multiple structs without breaking ABI.

Signed-off-by: Jacob Trimble <modmaker@google.com>
---
 libavutil/encryption_info.c | 148 ++++++++++++++++++++++++------------
 libavutil/encryption_info.h |   5 ++
 2 files changed, 104 insertions(+), 49 deletions(-)

diff --git a/libavutil/encryption_info.c b/libavutil/encryption_info.c
index a48ded922c..4675ceccf6 100644
--- a/libavutil/encryption_info.c
+++ b/libavutil/encryption_info.c
@@ -162,13 +162,16 @@  uint8_t *av_encryption_info_add_side_data(const AVEncryptionInfo *info, size_t *
 }
 
 // The format of the AVEncryptionInitInfo side data:
-// u32be system_id_size
-// u32be num_key_ids
-// u32be key_id_size
-// u32be data_size
-// u8[system_id_size] system_id
-// u8[key_id_size][num_key_id] key_ids
-// u8[data_size] data
+// u32be init_info_count
+// {
+//   u32be system_id_size
+//   u32be num_key_ids
+//   u32be key_id_size
+//   u32be data_size
+//   u8[system_id_size] system_id
+//   u8[key_id_size][num_key_id] key_ids
+//   u8[data_size] data
+// }[init_info_count]
 
 #define FF_ENCRYPTION_INIT_INFO_EXTRA 16
 
@@ -217,6 +220,7 @@  void av_encryption_init_info_free(AVEncryptionInitInfo *info)
         for (i = 0; i < info->num_key_ids; i++) {
             av_free(info->key_ids[i]);
         }
+        av_encryption_init_info_free(info->next);
         av_free(info->system_id);
         av_free(info->key_ids);
         av_free(info->data);
@@ -227,72 +231,118 @@  void av_encryption_init_info_free(AVEncryptionInitInfo *info)
 AVEncryptionInitInfo *av_encryption_init_info_get_side_data(
     const uint8_t *side_data, size_t side_data_size)
 {
-    AVEncryptionInitInfo *info;
-    uint64_t system_id_size, num_key_ids, key_id_size, data_size, i;
+    AVEncryptionInitInfo *ret = NULL, *info;
+    uint64_t system_id_size, num_key_ids, key_id_size, data_size, i, j;
+    uint64_t init_info_count;
 
-    if (!side_data || side_data_size < FF_ENCRYPTION_INIT_INFO_EXTRA)
+    if (!side_data || side_data_size < 4)
         return NULL;
 
-    system_id_size = AV_RB32(side_data);
-    num_key_ids = AV_RB32(side_data + 4);
-    key_id_size = AV_RB32(side_data + 8);
-    data_size = AV_RB32(side_data + 12);
+    init_info_count = AV_RB32(side_data);
+    side_data += 4;
+    side_data_size -= 4;
+    for (i = 0; i < init_info_count; i++) {
+        if (side_data_size < FF_ENCRYPTION_INIT_INFO_EXTRA) {
+            av_encryption_init_info_free(ret);
+            return NULL;
+        }
 
-    // UINT32_MAX + UINT32_MAX + UINT32_MAX * UINT32_MAX == UINT64_MAX
-    if (side_data_size - FF_ENCRYPTION_INIT_INFO_EXTRA < system_id_size + data_size + num_key_ids * key_id_size)
-        return NULL;
+        system_id_size = AV_RB32(side_data);
+        num_key_ids = AV_RB32(side_data + 4);
+        key_id_size = AV_RB32(side_data + 8);
+        data_size = AV_RB32(side_data + 12);
 
-    info = av_encryption_init_info_alloc(system_id_size, num_key_ids, key_id_size, data_size);
-    if (!info)
-        return NULL;
+        // UINT32_MAX + UINT32_MAX + UINT32_MAX * UINT32_MAX == UINT64_MAX
+        if (side_data_size - FF_ENCRYPTION_INIT_INFO_EXTRA < system_id_size + data_size + num_key_ids * key_id_size) {
+            av_encryption_init_info_free(ret);
+            return NULL;
+        }
+        side_data += FF_ENCRYPTION_INIT_INFO_EXTRA;
+        side_data_size -= FF_ENCRYPTION_INIT_INFO_EXTRA;
 
-    memcpy(info->system_id, side_data + 16, system_id_size);
-    side_data += system_id_size + 16;
-    for (i = 0; i < num_key_ids; i++) {
-      memcpy(info->key_ids[i], side_data, key_id_size);
-      side_data += key_id_size;
+        info = av_encryption_init_info_alloc(system_id_size, num_key_ids, key_id_size, data_size);
+        if (!info) {
+            av_encryption_init_info_free(ret);
+            return NULL;
+        }
+        info->next = ret;
+        ret = info;
+
+        memcpy(info->system_id, side_data, system_id_size);
+        side_data += system_id_size;
+        side_data_size -= system_id_size;
+        for (j = 0; j < num_key_ids; j++) {
+            memcpy(info->key_ids[j], side_data, key_id_size);
+            side_data += key_id_size;
+            side_data_size -= key_id_size;
+        }
+        memcpy(info->data, side_data, data_size);
+        side_data += data_size;
+        side_data_size -= data_size;
     }
-    memcpy(info->data, side_data, data_size);
 
-    return info;
+    return ret;
 }
 
 uint8_t *av_encryption_init_info_add_side_data(const AVEncryptionInitInfo *info, size_t *side_data_size)
 {
+    const AVEncryptionInitInfo *cur_info, *cur_info_2;
     uint8_t *buffer, *cur_buffer;
-    uint32_t i, max_size;
+    uint32_t i, init_info_count;
 
-    if (!info || !side_data_size ||
-        UINT32_MAX - FF_ENCRYPTION_INIT_INFO_EXTRA < info->system_id_size ||
-        UINT32_MAX - FF_ENCRYPTION_INIT_INFO_EXTRA - info->system_id_size < info->data_size) {
+    if (!info || !side_data_size)
         return NULL;
-    }
 
-    if (info->num_key_ids) {
-        max_size = UINT32_MAX - FF_ENCRYPTION_INIT_INFO_EXTRA - info->system_id_size - info->data_size;
-        if (max_size / info->num_key_ids < info->key_id_size)
+    *side_data_size = 4;
+    init_info_count = 0;
+    for (cur_info = info; cur_info; cur_info = cur_info->next) {
+        // Detect a circular list.
+        for (cur_info_2 = info; cur_info_2 != cur_info; cur_info_2 = cur_info_2->next) {
+            if (cur_info->next == cur_info_2)
+                return NULL;
+        }
+        if (cur_info->next == cur_info)
             return NULL;
+
+        if (UINT32_MAX == init_info_count ||
+            UINT32_MAX - *side_data_size < FF_ENCRYPTION_INIT_INFO_EXTRA ||
+            UINT32_MAX - *side_data_size - FF_ENCRYPTION_INIT_INFO_EXTRA < info->system_id_size ||
+            UINT32_MAX - *side_data_size - FF_ENCRYPTION_INIT_INFO_EXTRA - info->system_id_size < info->data_size) {
+            return NULL;
+        }
+        *side_data_size += FF_ENCRYPTION_INIT_INFO_EXTRA + info->system_id_size + info->data_size;
+        init_info_count++;
+
+        if (info->num_key_ids) {
+            if ((UINT32_MAX - *side_data_size) / info->num_key_ids < info->key_id_size) {
+                return NULL;
+            }
+            *side_data_size += info->num_key_ids * info->key_id_size;
+        }
     }
 
-    *side_data_size = FF_ENCRYPTION_INIT_INFO_EXTRA + info->system_id_size +
-                      info->data_size + (info->num_key_ids * info->key_id_size);
     cur_buffer = buffer = av_malloc(*side_data_size);
     if (!buffer)
         return NULL;
 
-    AV_WB32(cur_buffer,      info->system_id_size);
-    AV_WB32(cur_buffer +  4, info->num_key_ids);
-    AV_WB32(cur_buffer +  8, info->key_id_size);
-    AV_WB32(cur_buffer + 12, info->data_size);
-    cur_buffer += 16;
-
-    memcpy(cur_buffer, info->system_id, info->system_id_size);
-    cur_buffer += info->system_id_size;
-    for (i = 0; i < info->num_key_ids; i++) {
-        memcpy(cur_buffer, info->key_ids[i], info->key_id_size);
-        cur_buffer += info->key_id_size;
+    AV_WB32(cur_buffer, init_info_count);
+    cur_buffer += 4;
+    for (cur_info = info; cur_info; cur_info = cur_info->next) {
+        AV_WB32(cur_buffer,      info->system_id_size);
+        AV_WB32(cur_buffer +  4, info->num_key_ids);
+        AV_WB32(cur_buffer +  8, info->key_id_size);
+        AV_WB32(cur_buffer + 12, info->data_size);
+        cur_buffer += 16;
+
+        memcpy(cur_buffer, info->system_id, info->system_id_size);
+        cur_buffer += info->system_id_size;
+        for (i = 0; i < info->num_key_ids; i++) {
+            memcpy(cur_buffer, info->key_ids[i], info->key_id_size);
+            cur_buffer += info->key_id_size;
+        }
+        memcpy(cur_buffer, info->data, info->data_size);
+        cur_buffer += info->data_size;
     }
-    memcpy(cur_buffer, info->data, info->data_size);
 
     return buffer;
 }
diff --git a/libavutil/encryption_info.h b/libavutil/encryption_info.h
index ec5501aac7..9140968fde 100644
--- a/libavutil/encryption_info.h
+++ b/libavutil/encryption_info.h
@@ -115,6 +115,11 @@  typedef struct AVEncryptionInitInfo {
      */
     uint8_t* data;
     uint32_t data_size;
+
+    /**
+     * An optional pointer to the next initialization info in the list.
+     */
+    struct AVEncryptionInitInfo *next;
 } AVEncryptionInitInfo;
 
 /**
-- 
2.17.0.921.gf22659ad46-goog