File 0221-libslirp-udp-check-upd_input-buffer.patch of Package qemu.28156

From: Jose R Ziviani <jose.ziviani@suse.com>
Date: Tue, 6 Jul 2021 17:20:02 -0600
Subject: libslirp: udp: check upd_input buffer size
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Git-commit: 74572be49247c8c5feae7c6e0b50c4f569ca9824
References: bsc#1187367, CVE-2021-3594

Fixes: CVE-2021-3594
Fixes: https://gitlab.freedesktop.org/slirp/libslirp/-/issues/47

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Jose R Ziviani <jose.ziviani@suse.com>
---
 slirp/udp.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/slirp/udp.c b/slirp/udp.c
index c47870a61b453bb7004d369e4000..86c080b92484ed672d5ce50b8caf 100644
--- a/slirp/udp.c
+++ b/slirp/udp.c
@@ -92,7 +92,10 @@ udp_input(register struct mbuf *m, int iphlen)
 	/*
 	 * Get IP and UDP header together in first mbuf.
 	 */
-	ip = mtod(m, struct ip *);
+    ip = mtod_check(m, iphlen + sizeof(struct udphdr));
+    if (ip == NULL) {
+        goto bad;
+    }
 	uh = (struct udphdr *)((caddr_t)ip + iphlen);
 
 	/*