From 282914669483405a34000ed24b541201f8d29c4b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Yaroslav=20de=20la=20Pe=C3=B1a=20Smirnov?=
 <yps@yaroslavps.com>
Date: Wed, 10 Nov 2021 01:31:46 +0300
Subject: hashmap_remove: fix potential use-after-free

prev should be assigned before node is reassigned.
---
 Makefile      | 7 +++++--
 src/hashmap.c | 2 +-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index 79fd0e6..12944fe 100644
--- a/Makefile
+++ b/Makefile
@@ -1,9 +1,12 @@
-CFLAGS= -g -Wall -std=c99 -I.
+CFLAGS= -O0 -g -Wall -std=c99 -I.
 LDLIBS= 
 TESTFLAGS= $(CFLAGS) -Isrc/
 ifdef debug
 	CFLAGS+=-DDEBUG
 endif
+ifdef ASAN
+CFLAGS+= -fsanitize=address
+endif
 
 all: check
 bin:; mkdir -p bin/
@@ -19,4 +22,4 @@ check: bin/test_hashmap bin/test_template
 	for test in $^; do $$test || exit 1; done	
 
 .PHONY: clean 
-clean:; rm -r bin/
\ No newline at end of file
+clean:; rm -r bin/
diff --git a/src/hashmap.c b/src/hashmap.c
index 2522907..2787435 100644
--- a/src/hashmap.c
+++ b/src/hashmap.c
@@ -208,8 +208,8 @@ hashmap_remove(struct hashmap *hm, const char *key)
             return old_value;
         }
 
-        node = node->next;
         prev = node;
+        node = node->next;
     }
 
     return NULL;
-- 
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