From 6d7a53e9f16d2b18d94f9fce1e4eea34570286ef Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Thu, 24 Aug 2023 16:32:24 +0100 Subject: [PATCH] net/tap: Avoid variable-length array Use a heap allocation instead of a variable length array in tap_receive_iov(). The codebase has very few VLAs, and if we can get rid of them all we can make the compiler error on new additions. This is a defensive measure against security bugs where an on-stack dynamic allocation isn't correctly size-checked (e.g. CVE-2021-3527). Signed-off-by: Peter Maydell Reviewed-by: Francisco Iglesias Signed-off-by: Jason Wang --- net/tap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/tap.c b/net/tap.c index bcea8d03f9..c23d0323c2 100644 --- a/net/tap.c +++ b/net/tap.c @@ -118,10 +118,11 @@ static ssize_t tap_receive_iov(NetClientState *nc, const struct iovec *iov, { TAPState *s = DO_UPCAST(TAPState, nc, nc); const struct iovec *iovp = iov; - struct iovec iov_copy[iovcnt + 1]; + g_autofree struct iovec *iov_copy = NULL; struct virtio_net_hdr_mrg_rxbuf hdr = { }; if (s->host_vnet_hdr_len && !s->using_vnet_hdr) { + iov_copy = g_new(struct iovec, iovcnt + 1); iov_copy[0].iov_base = &hdr; iov_copy[0].iov_len = s->host_vnet_hdr_len; memcpy(&iov_copy[1], iov, iovcnt * sizeof(*iov)); -- 2.11.0