Issue with empty values in leaf-list

[achernavin22]

Suppose we have this field:

leaf-list ip {
    type inet:ipv4-prefix;
    ...
}

1. Assign one valid IP via REST (PUT "ip": "1.1.1.1/32" or "ip": ["1.1.1.1/32"])
2. Assign empty IP via REST (PUT "ip": "" or "ip": [""])
3. Segmentation fault

#0  __strcmp_sse42 () at ../sysdeps/x86_64/multiarch/strcmp-sse42.S:165
#1  0x00007f63252be163 in xml_cmp1 () from /lib64/libclixon.so.3
#2  0x00007f63252be4c3 in xml_search1 () from /lib64/libclixon.so.3
#3  0x00007f63252be5ee in xml_search () from /lib64/libclixon.so.3
#4  0x00007f63252bed75 in match_base_child () from /lib64/libclixon.so.3
#5  0x00007f63252c0271 in xml_diff1 () from /lib64/libclixon.so.3
#6  0x00007f63252c039b in xml_diff1 () from /lib64/libclixon.so.3
#7  0x00007f63252c039b in xml_diff1 () from /lib64/libclixon.so.3
#8  0x00007f63252c039b in xml_diff1 () from /lib64/libclixon.so.3
#9  0x00007f63252c039b in xml_diff1 () from /lib64/libclixon.so.3
#10 0x00007f63252c056a in xml_diff () from /lib64/libclixon.so.3
#11 0x00000000004083cf in validate_common ()
#12 0x0000000000408680 in candidate_commit ()
#13 0x0000000000408876 in from_client_commit ()
#14 0x0000000000407cef in from_client_msg ()
#15 0x0000000000408094 in from_client ()
#16 0x00007f63252b9fe4 in event_loop () from /lib64/libclixon.so.3
#17 0x0000000000405102 in main ()

OR

#0  __strcmp_sse42 () at ../sysdeps/x86_64/multiarch/strcmp-sse42.S:165
#1  0x00007f4b296cdfef in xml_cmp () from /lib64/libclixon.so.3
#2  0x00007f4b290fdd59 in msort_with_tmp (p=0x7ffdfe1beb50, b=0x1664310, n=2) at msort.c:83
#3  0x00007f4b290fe04c in msort_with_tmp (n=2, b=0x1664310, p=0x7ffdfe1beb50) at msort.c:45
#4  __GI___qsort_r (b=0x1664310, n=2, s=8, cmp=0x7f4b296cdeae <xml_cmp>, arg=<optimized out>) at msort.c:297
#5  0x00007f4b296ce27a in xml_sort () from /lib64/libclixon.so.3
#6  0x00007f4b296cd75c in xml_apply () from /lib64/libclixon.so.3
#7  0x00007f4b296cd795 in xml_apply () from /lib64/libclixon.so.3
#8  0x00007f4b296cd795 in xml_apply () from /lib64/libclixon.so.3
#9  0x00007f4b296cd795 in xml_apply () from /lib64/libclixon.so.3
#10 0x00007f4b296cd852 in xml_apply0 () from /lib64/libclixon.so.3
#11 0x0000000000406421 in from_client_edit_config ()
#12 0x0000000000407a89 in from_client_msg ()
#13 0x0000000000408094 in from_client ()
#14 0x00007f4b296c9fe4 in event_loop () from /lib64/libclixon.so.3
#15 0x0000000000405102 in main ()

This patch seems to solve the problem:

diff --git a/lib/src/clixon_xml_sort.c b/lib/src/clixon_xml_sort.c
index e3aa4b2..9731909 100644
--- a/lib/src/clixon_xml_sort.c
+++ b/lib/src/clixon_xml_sort.c
@@ -144,6 +144,12 @@ xml_cmp(const void* arg1,
        return 0; /* Ordered by user: maintain existing order */
     switch (y1->ys_keyword){
     case Y_LEAF_LIST: /* Match with name and value */
+       b1 = xml_body(x1);
+       b2 = xml_body(x2);
+       if (b1 == NULL || b2 == NULL) {
+           equal = 1;
+           break;
+       }
        equal = strcmp(xml_body(x1), xml_body(x2));
        break;
     case Y_LIST: /* Match with key values 
@@ -203,7 +209,8 @@ xml_cmp1(cxobj        *x,
     case Y_LEAF_LIST: /* Match with name and value */
        if (userorder && yang_find((yang_node*)y, Y_ORDERED_BY, "user") != NULL)
            *userorder=1;
-       b=xml_body(x);
+       if ((b = xml_body(x)) == NULL)
+           break; /* error case */
        match = strcmp(keyval[0], b);
        break;
     case Y_LIST: /* Match with array of key values */

[olofhagsand]

Empty leaf-list values was not thought about in this code. The same omission may appear elsewhere. Thanks for detecting!