diff options
| author | Russell Senior <russell@personaltelco.net> | 2021-03-16 01:24:18 -0700 |
|---|---|---|
| committer | Hauke Mehrtens <hauke@hauke-m.de> | 2021-03-29 22:16:54 +0200 |
| commit | 290b28664d2522654dd304c40122beeb85f565a6 (patch) | |
| tree | 22ed445d42c12f79653379ce1be54c73436f70cf /package | |
| parent | eb98c88f66d6d419d47ab951c2624ed6b18b4088 (diff) | |
| download | upstream-290b28664d2522654dd304c40122beeb85f565a6.tar.gz upstream-290b28664d2522654dd304c40122beeb85f565a6.tar.bz2 upstream-290b28664d2522654dd304c40122beeb85f565a6.zip | |
busybox: udhcpc, allow zero length dhcp options
This patch skips zero length DHCP options instead of failing.
Signed-off-by: Russell Senior <russell@personaltelco.net>
(cherry picked from commit 1c0436507156dc136d9e2668507817395434109e)
Diffstat (limited to 'package')
| -rw-r--r-- | package/utils/busybox/patches/205-udhcpc_allow_zero_length_options.patch | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/package/utils/busybox/patches/205-udhcpc_allow_zero_length_options.patch b/package/utils/busybox/patches/205-udhcpc_allow_zero_length_options.patch new file mode 100644 index 0000000000..abe8baf54f --- /dev/null +++ b/package/utils/busybox/patches/205-udhcpc_allow_zero_length_options.patch @@ -0,0 +1,49 @@ +From 7eed119b84b0f7efb7ef351940dd895dc2379eb3 Mon Sep 17 00:00:00 2001 +From: Russell Senior <russell@personaltelco.net> +Date: Mon, 15 Mar 2021 23:27:58 -0700 +Subject: [PATCH v2] udhcpc: ignore zero-length DHCP options + +Discovered that the DHCP server on a TrendNet router (unknown model) +provides a zero-length option 12 (Host Name) in the DHCP ACK message. This +has the effect of causing udhcpc to drop the rest of the options, including +option 51 (IP Address Lease Time), 3 (Router), and 6 (Domain Name Server), +most importantly leaving the OpenWrt device with no default gateway. + +The TrendNet behavior violates RFC 2132, which in Section 3.14 declares that +option 12 has a miniumum length of 1 octet. It is perhaps not a cosmic coincidence +that I found this behavior on Pi Day. + +This patch allows zero length options without bailing out, by simply skipping them. + +v2 changelog: +* advance the optionptr by two bytes, not one; +* add a message to warn about the rfc violation; + +Signed-off-by: Russell Senior <russell@personaltelco.net> +--- + networking/udhcp/common.c | 9 +++++++-- + 1 file changed, 7 insertions(+), 2 deletions(-) + +diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c +index 4bc719001..a16fd85d0 100644 +--- a/networking/udhcp/common.c ++++ b/networking/udhcp/common.c +@@ -277,8 +277,13 @@ uint8_t* FAST_FUNC udhcp_scan_options(struct dhcp_packet *packet, struct dhcp_sc + goto complain; /* complain and return NULL */ + len = 2 + scan_state->optionptr[OPT_LEN]; + scan_state->rem -= len; +- /* So far no valid option with length 0 known. */ +- if (scan_state->rem < 0 || scan_state->optionptr[OPT_LEN] == 0) ++ /* skip any options with zero length */ ++ if (scan_state->optionptr[OPT_LEN] == 0) { ++ scan_state->optionptr += 2; ++ bb_simple_error_msg("warning: zero length DHCP option violates rfc2132, skipping"); ++ continue; ++ } ++ if (scan_state->rem < 0) + goto complain; /* complain and return NULL */ + + if (scan_state->optionptr[OPT_CODE] == DHCP_OPTION_OVERLOAD) { +-- +2.30.1 + |