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Merge pull request #12249 from nmeum/pr/gnrc_tcp_option_length_access

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gnrc_tcp: check if option length field is present before accessing it
This commit is contained in:
benpicco 2019-09-17 23:22:53 +02:00 committed by GitHub
commit 7a818f0433
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 3 additions and 2 deletions
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1
sys/include/net/tcp.h
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@ -49,6 +49,7 @@ extern "C" {
* @brief TCP option "length"-field values.
* @{
*/
#define TCP_OPTION_LENGTH_MIN (2U) /**< Mimimum amount of bytes needed for an option with a length field */
#define TCP_OPTION_LENGTH_MSS (0x04) /**< MSS Option Size always 4 */
/** @} */

4
sys/net/gnrc/transport_layer/tcp/gnrc_tcp_option.c
View File

@ -51,7 +51,7 @@ int _option_parse(gnrc_tcp_tcb_t *tcb, tcp_hdr_t *hdr)
continue;
case TCP_OPTION_KIND_MSS:
if (option->length > opt_left || option->length != TCP_OPTION_LENGTH_MSS) {
if (opt_left < TCP_OPTION_LENGTH_MIN || option->length > opt_left || option->length != TCP_OPTION_LENGTH_MSS) {
DEBUG("gnrc_tcp_option.c : _option_parse() : invalid MSS Option length.\n");
return -1;
}
@ -66,7 +66,7 @@ int _option_parse(gnrc_tcp_tcb_t *tcb, tcp_hdr_t *hdr)
return -1;
}
if (option->length > opt_left) {
if (opt_left < TCP_OPTION_LENGTH_MIN || option->length > opt_left) {
DEBUG("gnrc_tcp_option.c : _option_parse() : invalid option length\n");
return 0;
}