diff: fix SEGV (NULL deref) in diff -N

1 files changed, 18 insertions, 9 deletions

diff --git a/coreutils/diff.c b/coreutils/diff.c
index fa6ef105e..911bfcf4d 100644
--- a/coreutils/diff.c
+++ b/coreutils/diff.c
@@ -997,24 +997,30 @@ static void do_diff(char *dir1, char *path1, char *dir2, char *path2)
 {
         int flags = D_HEADER;
         int val;
+        char *fullpath1 = NULL; /* if -N */
+        char *fullpath2 = NULL;
 
-        char *fullpath1 = concat_path_file(dir1, path1);
-        char *fullpath2 = concat_path_file(dir2, path2);
+        if (path1)
+                fullpath1 = concat_path_file(dir1, path1);
+        if (path2)
+                fullpath2 = concat_path_file(dir2, path2);
 
-        if (stat(fullpath1, &stb1) != 0) {
+        if (!fullpath1 || stat(fullpath1, &stb1) != 0) {
                 flags |= D_EMPTY1;
                 memset(&stb1, 0, sizeof(stb1));
-                if (ENABLE_FEATURE_CLEAN_UP)
+                if (path2) {
                         free(fullpath1);
-                fullpath1 = concat_path_file(dir1, path2);
+                        fullpath1 = concat_path_file(dir1, path2);
+                }
         }
-        if (stat(fullpath2, &stb2) != 0) {
+        if (!fullpath2 || stat(fullpath2, &stb2) != 0) {
                 flags |= D_EMPTY2;
                 memset(&stb2, 0, sizeof(stb2));
                 stb2.st_mode = stb1.st_mode;
-                if (ENABLE_FEATURE_CLEAN_UP)
+                if (path1) {
                         free(fullpath2);
-                fullpath2 = concat_path_file(dir2, path1);
+                        fullpath2 = concat_path_file(dir2, path1);
+                }
         }
 
         if (stb1.st_mode == 0)
@@ -1022,7 +1028,7 @@ static void do_diff(char *dir1, char *path1, char *dir2, char *path2)
 
         if (S_ISDIR(stb1.st_mode) && S_ISDIR(stb2.st_mode)) {
                 printf("Common subdirectories: %s and %s\n", fullpath1, fullpath2);
-                return;
+                goto ret;
         }
 
         if (!S_ISREG(stb1.st_mode) && !S_ISDIR(stb1.st_mode))
@@ -1033,6 +1039,9 @@ static void do_diff(char *dir1, char *path1, char *dir2, char *path2)
                 val = diffreg(fullpath1, fullpath2, flags);
 
         print_status(val, fullpath1, fullpath2, NULL);
+ ret:
+        free(fullpath1);
+        free(fullpath2);
 }
 #endif