From: Guy Harris <gharris@sonic.net>
Date: Fri, 1 Apr 2022 22:28:33 +0000 (-0700)
Subject: Fail if nd_push_buffer() or nd_push_snaplen() fails.
X-Git-Url: https://git.tcpdump.org/tcpdump/commitdiff_plain/e84f58700fe17ee5c4680247fcdcf506ff38587d

Fail if nd_push_buffer() or nd_push_snaplen() fails.

Always call ndo->ndo_error with a memory-allocation error if they fail.

Add WARN_UNUSED_RESULT for compilers that support it, and use it for
those routines, so that any future code that doesn't check for failure
gets a warning.
---

diff --git a/funcattrs.h b/funcattrs.h
index 02a0a74f..21f3cc1d 100644
--- a/funcattrs.h
+++ b/funcattrs.h
@@ -87,6 +87,19 @@
   #define NORETURN_FUNCPTR
 #endif
 
+/*
+ * WARN_UNUSED_RESULT, before a function declaration, means "the caller
+ * should use the result of this function" (even if it's just a success/
+ * failure indication).
+ */
+#if __has_attribute(warn_unused_result) \
+    || ND_IS_AT_LEAST_GNUC_VERSION(3,4) \
+    || ND_IS_AT_LEAST_HP_C_VERSION(6,25)
+  #define WARN_UNUSED_RESULT __attribute((warn_unused_result))
+#else
+  #define WARN_UNUSED_RESULT
+#endif
+
 /*
  * PRINTFLIKE(x,y), after a function declaration, means "this function
  * does printf-style formatting, with the xth argument being the format
diff --git a/netdissect.h b/netdissect.h
index f53499e9..909b7c87 100644
--- a/netdissect.h
+++ b/netdissect.h
@@ -262,9 +262,10 @@ struct netdissect_options {
 		      PRINTFLIKE_FUNCPTR(2, 3);
 };
 
-extern int nd_push_buffer(netdissect_options *, u_char *, const u_char *,
-    u_int);
-extern int nd_push_snaplen(netdissect_options *, const u_char *, u_int);
+extern WARN_UNUSED_RESULT int nd_push_buffer(netdissect_options *, u_char *,
+    const u_char *, u_int);
+extern WARN_UNUSED_RESULT int nd_push_snaplen(netdissect_options *,
+    const u_char *, u_int);
 extern void nd_change_snaplen(netdissect_options *, const u_char *, u_int);
 extern void nd_pop_packet_info(netdissect_options *);
 extern void nd_pop_all_packet_info(netdissect_options *);
diff --git a/print-esp.c b/print-esp.c
index 22af35b3..fb94a60a 100644
--- a/print-esp.c
+++ b/print-esp.c
@@ -331,7 +331,8 @@ int esp_decrypt_buffer_by_ikev2_print(netdissect_options *ndo,
 	 */
 	if (!nd_push_buffer(ndo, pt, pt, ctlen)) {
 		free(pt);
-		return 0;
+		(*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC,
+			"%s: can't push buffer on buffer stack", __func__);
 	}
 
 	return 1;
@@ -907,7 +908,10 @@ esp_print(netdissect_options *ndo,
 	 * Don't put padding + padding length(1 byte) + next header(1 byte)
 	 * in the buffer because they are not part of the plaintext to decode.
 	 */
-	nd_push_snaplen(ndo, pt, payloadlen - (padlen + 2));
+	if (!nd_push_snaplen(ndo, pt, payloadlen - (padlen + 2))) {
+		(*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC,
+			"%s: can't push snaplen on buffer stack", __func__);
+	}
 
 	/* Now dissect the plaintext. */
 	ip_demux_print(ndo, pt, payloadlen - (padlen + 2), ver, fragmented,
diff --git a/print-ether.c b/print-ether.c
index 1b273e16..b1865d17 100644
--- a/print-ether.c
+++ b/print-ether.c
@@ -306,7 +306,10 @@ recurse:
 		 * Cut off the snapshot length to the end of the
 		 * payload.
 		 */
-		nd_push_snaplen(ndo, p, length);
+		if (!nd_push_snaplen(ndo, p, length)) {
+			(*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC,
+				"%s: can't push snaplen on buffer stack", __func__);
+		}
 
 		if (ndo->ndo_eflag) {
 			ND_PRINT("802.3");
diff --git a/print-ip.c b/print-ip.c
index 4f9617a3..23ba99c9 100644
--- a/print-ip.c
+++ b/print-ip.c
@@ -377,7 +377,10 @@ ip_print(netdissect_options *ndo,
 	/*
 	 * Cut off the snapshot length to the end of the IP payload.
 	 */
-	nd_push_snaplen(ndo, bp, len);
+	if (!nd_push_snaplen(ndo, bp, len)) {
+		(*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC,
+			"%s: can't push snaplen on buffer stack", __func__);
+	}
 
 	len -= hlen;
 
diff --git a/print-ip6.c b/print-ip6.c
index 15b30630..82948334 100644
--- a/print-ip6.c
+++ b/print-ip6.c
@@ -305,7 +305,10 @@ ip6_print(netdissect_options *ndo, const u_char *bp, u_int length)
 	/*
 	 * Cut off the snapshot length to the end of the IP payload.
 	 */
-	nd_push_snaplen(ndo, bp, len);
+	if (!nd_push_snaplen(ndo, bp, len)) {
+		(*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC,
+			"%s: can't push snaplen on buffer stack", __func__);
+	}
 
 	cp = (const u_char *)ip6;
 	advance = sizeof(struct ip6_hdr);