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relay: fix crash when decoding a malformed websocket frame (CVE-2021-40516)

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This commit is contained in:
Sébastien Helleu 2021-09-07 19:05:06 +02:00
parent 6f352deefe
commit 24f4f8fffa
2 changed files with 18 additions and 5 deletions
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7
ChangeLog.adoc
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@ -15,6 +15,13 @@ https://weechat.org/files/releasenotes/ReleaseNotes-devel.html[release notes]
(file _ReleaseNotes.adoc_ in sources).
[[v2.3.1]]
== Version 2.3.1 (under dev)
Bug fixes::
* relay: fix crash when decoding a malformed websocket frame (CVE-2021-40516)
[[v2.3]]
== Version 2.3 (2018-10-21)

16
src/plugins/relay/relay-websocket.c
View File

@ -278,7 +278,7 @@ relay_websocket_decode_frame (const unsigned char *buffer,
index_buffer = 0;
/* loop to decode all frames in message */
while (index_buffer + 2 <= buffer_length)
while (index_buffer + 1 < buffer_length)
{
opcode = buffer[index_buffer] & 15;
@ -293,10 +293,12 @@ relay_websocket_decode_frame (const unsigned char *buffer,
length_frame_size = 1;
length_frame = buffer[index_buffer + 1] & 127;
index_buffer += 2;
if (index_buffer >= buffer_length)
return 0;
if ((length_frame == 126) || (length_frame == 127))
{
length_frame_size = (length_frame == 126) ? 2 : 8;
if (buffer_length < 1 + length_frame_size)
if (index_buffer + length_frame_size > buffer_length)
return 0;
length_frame = 0;
for (i = 0; i < length_frame_size; i++)
@ -306,10 +308,9 @@ relay_websocket_decode_frame (const unsigned char *buffer,
index_buffer += length_frame_size;
}
if (buffer_length < 1 + length_frame_size + 4 + length_frame)
return 0;
/* read masks (4 bytes) */
if (index_buffer + 4 > buffer_length)
return 0;
int masks[4];
for (i = 0; i < 4; i++)
{
@ -323,6 +324,11 @@ relay_websocket_decode_frame (const unsigned char *buffer,
*decoded_length += 1;
/* decode data using masks */
if ((length_frame > buffer_length)
|| (index_buffer + length_frame > buffer_length))
{
return 0;
}
for (i = 0; i < length_frame; i++)
{
decoded[*decoded_length + i] = (int)((unsigned char)buffer[index_buffer + i]) ^ masks[i % 4];