URL:
https://github.com/SSSD/sssd/pull/455
Title: #455: mmap_cache: make checks independent of input size
fidencio commented:
"""
Sorry for jumping in a patch set which I'm neither the author nor the reviewer.
Covscan has found an issue with this patchset:
```
Error: NULL_RETURNS (CWE-476): [#def1]
sssd-1.16.1/src/responder/nss/nss_protocol.c:162: returned_null: "memchr"
returns null (checked 7 out of 8 times).
sssd-1.16.1/src/responder/nss/nsssrv_mmap_cache.c:557: example_checked: Example 1:
"memchr(t_key, 0, strs_offset + strs_len - name_ptr)" has its value checked in
"memchr(t_key, 0, strs_offset + strs_len - name_ptr) == NULL".
sssd-1.16.1/src/sss_client/idmap/sss_nss_idmap.c:171: example_assign: Example 2:
Assigning: "p" = return value from "memchr(p, 0, buf_len - (p -
buf))".
sssd-1.16.1/src/sss_client/idmap/sss_nss_idmap.c:172: example_checked: Example 2 (cont.):
"p" has its value checked in "p == NULL".
sssd-1.16.1/src/sss_client/nss_mc_group.c:157: example_checked: Example 3:
"memchr(rec_name, 0, 16UL + data->strs_len - data->name)" has its value
checked in "memchr(rec_name, 0, 16UL + data->strs_len - data->name) ==
NULL".
sssd-1.16.1/src/sss_client/nss_mc_initgr.c:139: example_checked: Example 4:
"memchr(rec_name, 0, 24UL + data->data_len - data->name)" has its value
checked in "memchr(rec_name, 0, 24UL + data->data_len - data->name) ==
NULL".
sssd-1.16.1/src/sss_client/nss_mc_passwd.c:150: example_checked: Example 5:
"memchr(rec_name, 0, 16UL + data->strs_len - data->name)" has its value
checked in "memchr(rec_name, 0, 16UL + data->strs_len - data->name) ==
NULL".
sssd-1.16.1/src/responder/nss/nss_protocol.c:162: var_assigned: Assigning: "p" =
null return value from "memchr".
sssd-1.16.1/src/responder/nss/nss_protocol.c:176: dereference: Incrementing a pointer
which might be null: "p".
# 174| }
# 175|
# 176|-> p++;
# 177| if ((p - body) + sizeof(uint32_t) != blen) {
# 178| DEBUG(SSSDBG_CRIT_FAILURE, "Body has unexpected size!\n");
```
"""
See the full comment at
https://github.com/SSSD/sssd/pull/455#issuecomment-346051695