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| author | Denys Vlasenko | 2018-12-17 18:07:18 +0100 |
|---|---|---|
| committer | Denys Vlasenko | 2018-12-17 18:07:18 +0100 |
| commit | 6d3b4bb24da9a07c263f3c1acf8df85382ff562c (patch) | |
| tree | 62b1094f93c955774e8b2d4aee798029a5a71b7d /networking/udhcp/common.c | |
| parent | 4b72aebe80aaa50a765d5ff61d7d67ed731502d9 (diff) | |
| download | busybox-6d3b4bb24da9a07c263f3c1acf8df85382ff562c.zip busybox-6d3b4bb24da9a07c263f3c1acf8df85382ff562c.tar.gz | |
udhcpc: check that 4-byte options are indeed 4-byte, closes 11506
function old new delta
udhcp_get_option32 - 27 +27
udhcp_get_option 231 248 +17
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(add/remove: 1/0 grow/shrink: 1/0 up/down: 44/0) Total: 44 bytes
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'networking/udhcp/common.c')
| -rw-r--r-- | networking/udhcp/common.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c index e5fd74f..41b05b8 100644 --- a/networking/udhcp/common.c +++ b/networking/udhcp/common.c @@ -272,6 +272,15 @@ uint8_t* FAST_FUNC udhcp_get_option(struct dhcp_packet *packet, int code) goto complain; /* complain and return NULL */ if (optionptr[OPT_CODE] == code) { + if (optionptr[OPT_LEN] == 0) { + /* So far no valid option with length 0 known. + * Having this check means that searching + * for DHCP_MESSAGE_TYPE need not worry + * that returned pointer might be unsafe + * to dereference. + */ + goto complain; /* complain and return NULL */ + } log_option("option found", optionptr); return optionptr + OPT_DATA; } @@ -289,6 +298,16 @@ uint8_t* FAST_FUNC udhcp_get_option(struct dhcp_packet *packet, int code) return NULL; } +uint8_t* FAST_FUNC udhcp_get_option32(struct dhcp_packet *packet, int code) +{ + uint8_t *r = udhcp_get_option(packet, code); + if (r) { + if (r[-1] != 4) + r = NULL; + } + return r; +} + /* Return the position of the 'end' option (no bounds checking) */ int FAST_FUNC udhcp_end_option(uint8_t *optionptr) { |