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Ensure memcpy of mac lengths does not overflow buffers #18757

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merged 4 commits into from
May 25, 2022
Merged

Ensure memcpy of mac lengths does not overflow buffers #18757

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15854de
Ensure memcpy of mac lengths does not overflow buffers
andy31415 May 24, 2022
1d6e4fc
Ensure 0 memset in case mac address is too short
andy31415 May 24, 2022
583bf74
Use std::min instead of explicit if
andy31415 May 25, 2022
b8748e6
Add missing include and cast for std::min
andy31415 May 25, 2022
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14 changes: 13 additions & 1 deletion src/platform/Linux/ConfigurationManagerImpl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -130,13 +130,25 @@ CHIP_ERROR ConfigurationManagerImpl::GetPrimaryWiFiMACAddress(uint8_t * buf)
CHIP_ERROR error = CHIP_NO_ERROR;
bool found = false;

// TODO: ideally the buffer size should have been passed as a span, however
// for now use the size that is validated in GenericConfigurationManagerImpl.ipp
constexpr size_t kExpectedBufMinSize = ConfigurationManager::kPrimaryMACAddressLength;
memset(buf, 0, kExpectedBufMinSize);

VerifyOrExit(getifaddrs(&addresses) == 0, error = CHIP_ERROR_INTERNAL);
for (auto addr = addresses; addr != nullptr; addr = addr->ifa_next)
{
if ((addr->ifa_addr) && (addr->ifa_addr->sa_family == AF_PACKET) && strncmp(addr->ifa_name, "lo", IFNAMSIZ) != 0)
{
struct sockaddr_ll * mac = (struct sockaddr_ll *) addr->ifa_addr;
memcpy(buf, mac->sll_addr, mac->sll_halen);

size_t mac_len = mac->sll_halen;
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if (mac_len > kExpectedBufMinSize)
{
mac_len = kExpectedBufMinSize;
}

memcpy(buf, mac->sll_addr, mac_len);
found = true;
break;
}
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