From 1a708ece1ad8b924466e81c5fcdf4e22311fd770 Mon Sep 17 00:00:00 2001
From: Alexey Izbyshev <izbyshev@ispras.ru>
Date: Mon, 27 Feb 2023 23:05:16 +0300
Subject: getifaddrs: fix UB via taking address of null pointer union
dereference
getifaddrs computes &ctx->first->ifa even if ctx->first is NULL. While
this shouldn't be possible on the success path because the loopback
interface is hardcoded into the kernel, this is still possible on the
error path (for example, if __rtnetlink_enumerate couldn't create a
socket due to exceeding the fd limit).
---
src/network/getifaddrs.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
(limited to 'src/network')
diff --git a/src/network/getifaddrs.c b/src/network/getifaddrs.c
index fed75bd8..74df4d6c 100644
--- a/src/network/getifaddrs.c
+++ b/src/network/getifaddrs.c
@@ -39,8 +39,8 @@ struct ifaddrs_storage {
};
struct ifaddrs_ctx {
- struct ifaddrs_storage *first;
- struct ifaddrs_storage *last;
+ struct ifaddrs *first;
+ struct ifaddrs *last;
struct ifaddrs_storage *hash[IFADDRS_HASH_SIZE];
};
@@ -195,9 +195,9 @@ static int netlink_msg_to_ifaddr(void *pctx, struct nlmsghdr *h)
}
if (ifs->ifa.ifa_name) {
- if (!ctx->first) ctx->first = ifs;
- if (ctx->last) ctx->last->ifa.ifa_next = &ifs->ifa;
- ctx->last = ifs;
+ if (!ctx->first) ctx->first = &ifs->ifa;
+ if (ctx->last) ctx->last->ifa_next = &ifs->ifa;
+ ctx->last = &ifs->ifa;
} else {
free(ifs);
}
@@ -210,7 +210,7 @@ int getifaddrs(struct ifaddrs **ifap)
int r;
memset(ctx, 0, sizeof *ctx);
r = __rtnetlink_enumerate(AF_UNSPEC, AF_UNSPEC, netlink_msg_to_ifaddr, ctx);
- if (r == 0) *ifap = &ctx->first->ifa;
- else freeifaddrs(&ctx->first->ifa);
+ if (r == 0) *ifap = ctx->first;
+ else freeifaddrs(ctx->first);
return r;
}
--
cgit v1.2.3-70-g09d2