74 lines
3.4 KiB
Diff
74 lines
3.4 KiB
Diff
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From 3c4de6e36c4d387a648622e7b828a05f2b1b47e6 Mon Sep 17 00:00:00 2001
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From: Denys Vlasenko <vda.linux@googlemail.com>
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Date: Fri, 26 Feb 2016 15:54:56 +0100
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Subject: [PATCH] udhcpc: fix OPTION_6RD parsing (could overflow its malloced
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buffer)
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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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(cherry picked from commit 352f79acbd759c14399e39baef21fc4ffe180ac2)
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Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
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---
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networking/udhcp/common.c | 15 +++++++++++++--
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networking/udhcp/dhcpc.c | 4 ++--
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2 files changed, 15 insertions(+), 4 deletions(-)
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diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c
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index bc41c8d..680852c 100644
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--- a/networking/udhcp/common.c
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+++ b/networking/udhcp/common.c
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@@ -142,7 +142,7 @@ const char dhcp_option_strings[] ALIGN1 =
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* udhcp_str2optset: to determine how many bytes to allocate.
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* xmalloc_optname_optval: to estimate string length
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* from binary option length: (option[LEN] / dhcp_option_lengths[opt_type])
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- * is the number of elements, multiply in by one element's string width
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+ * is the number of elements, multiply it by one element's string width
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* (len_of_option_as_string[opt_type]) and you know how wide string you need.
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*/
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const uint8_t dhcp_option_lengths[] ALIGN1 = {
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@@ -162,7 +162,18 @@ const uint8_t dhcp_option_lengths[] ALIGN1 = {
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[OPTION_S32] = 4,
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/* Just like OPTION_STRING, we use minimum length here */
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[OPTION_STATIC_ROUTES] = 5,
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- [OPTION_6RD] = 22, /* ignored by udhcp_str2optset */
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+ [OPTION_6RD] = 12, /* ignored by udhcp_str2optset */
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+ /* The above value was chosen as follows:
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+ * len_of_option_as_string[] for this option is >60: it's a string of the form
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+ * "32 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 ".
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+ * Each additional ipv4 address takes 4 bytes in binary option and appends
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+ * another "255.255.255.255 " 16-byte string. We can set [OPTION_6RD] = 4
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+ * but this severely overestimates string length: instead of 16 bytes,
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+ * it adds >60 for every 4 bytes in binary option.
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+ * We cheat and declare here that option is in units of 12 bytes.
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+ * This adds more than 60 bytes for every three ipv4 addresses - more than enough.
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+ * (Even 16 instead of 12 should work, but let's be paranoid).
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+ */
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};
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diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
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index 915f659..2332b57 100644
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--- a/networking/udhcp/dhcpc.c
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+++ b/networking/udhcp/dhcpc.c
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@@ -113,7 +113,7 @@ static const uint8_t len_of_option_as_string[] = {
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[OPTION_IP ] = sizeof("255.255.255.255 "),
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[OPTION_IP_PAIR ] = sizeof("255.255.255.255 ") * 2,
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[OPTION_STATIC_ROUTES ] = sizeof("255.255.255.255/32 255.255.255.255 "),
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- [OPTION_6RD ] = sizeof("32 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 "),
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+ [OPTION_6RD ] = sizeof("132 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 "),
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[OPTION_STRING ] = 1,
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[OPTION_STRING_HOST ] = 1,
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#if ENABLE_FEATURE_UDHCP_RFC3397
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@@ -220,7 +220,7 @@ static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_
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type = optflag->flags & OPTION_TYPE_MASK;
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optlen = dhcp_option_lengths[type];
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upper_length = len_of_option_as_string[type]
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- * ((unsigned)(len + optlen - 1) / (unsigned)optlen);
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+ * ((unsigned)(len + optlen) / (unsigned)optlen);
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dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
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dest += sprintf(ret, "%s=", opt_name);
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--
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2.7.4
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