I noticed a commit in connman: "gdhcp: Avoid leaking stack data via unitiialized variable" [1]
Since gdhcp is just BusyBox udhcp with the serial numbers filed off, I checked if BusyBox udhcp has a related issue. The issue is that the get_option logic assumes any data within the memory area of the buffer is "valid". This reduces the complexity of the function at the cost of reading past the end of the actually received data in the case of specially crafted packets. This is not a problem for the udhcp_recv_kernel_packet data path as the entire memory area is zeroed. However, d4/d6_recv_raw_packet does not zero the memory. Note that a related commit [2] is not required as we are zeroing any data that can be read by the get_option function. [1] https://git.kernel.org/pub/scm/network/connman/connman.git/commit/?id=a74524b3e3fad81b0fd1084ffdf9f2ea469cd9b1 [2] https://git.kernel.org/pub/scm/network/connman/connman.git/commit/?id=58d397ba74873384aee449690a9070bacd5676fa Signed-off-by: Russ Dill <[email protected]> Cc: Colin Wee <[email protected]> Cc: Denys Vlasenko <[email protected]> --- networking/udhcp/d6_dhcpc.c | 1 + networking/udhcp/dhcpc.c | 1 + 2 files changed, 2 insertions(+) diff --git a/networking/udhcp/d6_dhcpc.c b/networking/udhcp/d6_dhcpc.c index cdd06188e..a72fd31bd 100644 --- a/networking/udhcp/d6_dhcpc.c +++ b/networking/udhcp/d6_dhcpc.c @@ -961,6 +961,7 @@ static NOINLINE int d6_recv_raw_packet(struct in6_addr *peer_ipv6, struct d6_pac d6_dump_packet(&packet.data); bytes -= sizeof(packet.ip6) + sizeof(packet.udp); + memset(d6_pkt, 0, sizeof(*d6_pkt)); memcpy(d6_pkt, &packet.data, bytes); return bytes; } diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c index 200a2fb8a..fc86b1607 100644 --- a/networking/udhcp/dhcpc.c +++ b/networking/udhcp/dhcpc.c @@ -981,6 +981,7 @@ static NOINLINE int d4_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd) udhcp_dump_packet(&packet.data); bytes -= sizeof(packet.ip) + sizeof(packet.udp); + memset(dhcp_pkt, 0, sizeof(*dhcp_pkt)); memcpy(dhcp_pkt, &packet.data, bytes); return bytes; } -- 2.40.1 _______________________________________________ busybox mailing list [email protected] http://lists.busybox.net/mailman/listinfo/busybox
