On Tue, Jul 4, 2023 at 11:03 AM Marc-André Lureau
<[email protected]> wrote:
>
>
>
> On Tue, Jul 4, 2023 at 10:42 AM Mauro Matteo Cascella <[email protected]>
> wrote:
>>
>> A wrong exit condition may lead to an infinite loop when inflating a
>> valid zlib buffer containing some extra bytes in the `inflate_buffer`
>> function. The bug only occurs post-authentication. Return the buffer
>> immediately if the end of the compressed data has been reached
>> (Z_STREAM_END).
>>
>> Fixes: CVE-2023-3255
>> Fixes: 0bf41cab ("ui/vnc: clipboard support")
>> Reported-by: Kevin Denis <[email protected]>
>> Signed-off-by: Mauro Matteo Cascella <[email protected]>
>
>
> Tested-by: Marc-André Lureau <[email protected]>
> Reviewed-by: Marc-André Lureau <[email protected]>
>
> Note: we may want to disconnect the client when there are extra bytes in the
> message, or print some warnings.
Sure, I guess we can call vnc_disconnect_finish or vnc_client_error
for disconnecting, not sure how to properly print warnings. Feel free
to add that yourself when applying the patch. Or I can try to send v2
if you prefer.
Thanks,
>>
>> ---
>> ui/vnc-clipboard.c | 10 ++++------
>> 1 file changed, 4 insertions(+), 6 deletions(-)
>>
>> diff --git a/ui/vnc-clipboard.c b/ui/vnc-clipboard.c
>> index 8aeadfaa21..c759be3438 100644
>> --- a/ui/vnc-clipboard.c
>> +++ b/ui/vnc-clipboard.c
>> @@ -50,8 +50,11 @@ static uint8_t *inflate_buffer(uint8_t *in, uint32_t
>> in_len, uint32_t *size)
>> ret = inflate(&stream, Z_FINISH);
>> switch (ret) {
>> case Z_OK:
>> - case Z_STREAM_END:
>> break;
>> + case Z_STREAM_END:
>> + *size = stream.total_out;
>> + inflateEnd(&stream);
>> + return out;
>> case Z_BUF_ERROR:
>> out_len <<= 1;
>> if (out_len > (1 << 20)) {
>> @@ -66,11 +69,6 @@ static uint8_t *inflate_buffer(uint8_t *in, uint32_t
>> in_len, uint32_t *size)
>> }
>> }
>>
>> - *size = stream.total_out;
>> - inflateEnd(&stream);
>> -
>> - return out;
>> -
>> err_end:
>> inflateEnd(&stream);
>> err:
>> --
>> 2.41.0
>>
>>
>
>
> --
> Marc-André Lureau
--
Mauro Matteo Cascella
Red Hat Product Security
PGP-Key ID: BB3410B0
