BUG/MINOR: compression: Missing calloc return value check in comp_append_type/algo

A memory allocation failure happening in comp_append_type or
comp_append_algo called while parsing compression options would have
resulted in a crash. These functions are only called during
configuration parsing.

It was raised in GitHub issue #1233.
It could be backported to all stable branches.

(cherry picked from commit 6443bcc2e1f2e1e11af76ef460d8241f06223de8)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit a3a8d50d992ab145e5c353cc36e8a787d3aead57)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/src/flt_http_comp.c b/src/flt_http_comp.c
index fb66947..cdb9f04 100644
--- a/src/flt_http_comp.c
+++ b/src/flt_http_comp.c
@@ -638,11 +638,17 @@
 			return -1;
 		}
 		while (*(args[cur_arg])) {
-			if (comp_append_algo(comp, args[cur_arg]) < 0) {
-				memprintf(err, "'%s' : '%s' is not a supported algorithm.\n",
-					  args[0], args[cur_arg]);
+			int retval = comp_append_algo(comp, args[cur_arg]);
+			if (retval) {
+				if (retval < 0)
+					memprintf(err, "'%s' : '%s' is not a supported algorithm.\n",
+						  args[0], args[cur_arg]);
+				else
+					memprintf(err, "'%s' : out of memory while parsing algo '%s'.\n",
+						  args[0], args[cur_arg]);
 				return -1;
 			}
+
 			if (proxy->comp->algos->init(&ctx, 9) == 0)
 				proxy->comp->algos->end(&ctx);
 			else {
@@ -664,7 +670,10 @@
 			return -1;
 		}
 		while (*(args[cur_arg])) {
-			comp_append_type(comp, args[cur_arg]);
+			if (comp_append_type(comp, args[cur_arg])) {
+				memprintf(err, "'%s': out of memory.", args[0]);
+				return -1;
+			}
 			cur_arg++;
 			continue;
 		}