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resolved: simplify alloc size calculation

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The allocation size was calculated in a complicated way, and for values
close to the page size we would actually allocate less than requested.

Reported by Chris Coulson <chris.coulson@canonical.com>.

CVE-2017-9445
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2017-06-18 16:07:57 -04:00
parent 751ca3f1de
commit db848813ba
2 changed files with 1 additions and 9 deletions
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8
src/resolve/resolved-dns-packet.c
View file

@ -47,13 +47,7 @@ int dns_packet_new(DnsPacket **ret, DnsProtocol protocol, size_t mtu) {
assert(ret);
if (mtu <= UDP_PACKET_HEADER_SIZE)
a = DNS_PACKET_SIZE_START;
else
a = mtu - UDP_PACKET_HEADER_SIZE;
if (a < DNS_PACKET_HEADER_SIZE)
a = DNS_PACKET_HEADER_SIZE;
a = MAX(mtu, DNS_PACKET_HEADER_SIZE);
/* round up to next page size */
a = PAGE_ALIGN(ALIGN(sizeof(DnsPacket)) + a) - ALIGN(sizeof(DnsPacket));

2
src/resolve/resolved-dns-packet.h
View file

@ -66,8 +66,6 @@ struct DnsPacketHeader {
/* With EDNS0 we can use larger packets, default to 4096, which is what is commonly used */
#define DNS_PACKET_UNICAST_SIZE_LARGE_MAX 4096
#define DNS_PACKET_SIZE_START 512
struct DnsPacket {
int n_ref;
DnsProtocol protocol;