src/os/unix/ngx_readv_chain.c:70: error: Null Dereference
  pointer `iov` last assigned on line 57 could be null and is dereferenced at line 70, column 13.

src/os/unix/ngx_readv_chain.c:13:1: start of procedure ngx_readv_chain()
11. 
12. 
13. ssize_t
    ^
14. ngx_readv_chain(ngx_connection_t *c, ngx_chain_t *chain)
15. {

src/os/unix/ngx_readv_chain.c:23:5: 
21.     struct iovec  *iov, iovs[NGX_IOVS_PREALLOCATE];
22. 
23.     rev = c->read;
        ^
24. 
25. #if (NGX_HAVE_KQUEUE)

src/os/unix/ngx_readv_chain.c:56:5: 
54. #endif
55. 
56.     prev = NULL;
        ^
57.     iov = NULL;
58.     size = 0;

src/os/unix/ngx_readv_chain.c:57:5: 
55. 
56.     prev = NULL;
57.     iov = NULL;
        ^
58.     size = 0;
59. 

src/os/unix/ngx_readv_chain.c:58:5: 
56.     prev = NULL;
57.     iov = NULL;
58.     size = 0;
        ^
59. 
60.     vec.elts = iovs;

src/os/unix/ngx_readv_chain.c:60:5: 
58.     size = 0;
59. 
60.     vec.elts = iovs;
        ^
61.     vec.nelts = 0;
62.     vec.size = sizeof(struct iovec);

src/os/unix/ngx_readv_chain.c:61:5: 
59. 
60.     vec.elts = iovs;
61.     vec.nelts = 0;
        ^
62.     vec.size = sizeof(struct iovec);
63.     vec.nalloc = NGX_IOVS_PREALLOCATE;

src/os/unix/ngx_readv_chain.c:62:5: 
60.     vec.elts = iovs;
61.     vec.nelts = 0;
62.     vec.size = sizeof(struct iovec);
        ^
63.     vec.nalloc = NGX_IOVS_PREALLOCATE;
64.     vec.pool = c->pool;

src/os/unix/ngx_readv_chain.c:63:5: 
61.     vec.nelts = 0;
62.     vec.size = sizeof(struct iovec);
63.     vec.nalloc = NGX_IOVS_PREALLOCATE;
        ^
64.     vec.pool = c->pool;
65. 

src/os/unix/ngx_readv_chain.c:64:5: 
62.     vec.size = sizeof(struct iovec);
63.     vec.nalloc = NGX_IOVS_PREALLOCATE;
64.     vec.pool = c->pool;
        ^
65. 
66.     /* coalesce the neighbouring bufs */

src/os/unix/ngx_readv_chain.c:68:12: Loop condition is true. Entering loop body
66.     /* coalesce the neighbouring bufs */
67. 
68.     while (chain) {
               ^
69.         if (prev == chain->buf->last) {
70.             iov->iov_len += chain->buf->end - chain->buf->last;

src/os/unix/ngx_readv_chain.c:69:13: Taking true branch
67. 
68.     while (chain) {
69.         if (prev == chain->buf->last) {
                ^
70.             iov->iov_len += chain->buf->end - chain->buf->last;
71. 

src/os/unix/ngx_readv_chain.c:70:13: 
68.     while (chain) {
69.         if (prev == chain->buf->last) {
70.             iov->iov_len += chain->buf->end - chain->buf->last;
                ^
71. 
72.         } else {
