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Fix 'Dereference of null pointer' from scan-build-10

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These are mostly false positives, the clang-analyzer FAQ[1] specifies
why and how to fix it:

> The reason the analyzer often thinks that a pointer can be null is
> because the preceding code checked compared it against null. So if you
> are absolutely sure that it cannot be null, remove the preceding check
> and, preferably, add an assertion as well.

The 2 warnings reported are:

dnssec-cds.c:781:4: warning: Access to field 'base' results in a dereference of a null pointer (loaded from variable 'buf')
                        isc_buffer_availableregion(buf, &r);
                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/builds/isc-projects/bind9/lib/isc/include/isc/buffer.h:996:36: note: expanded from macro 'isc_buffer_availableregion'
                                   ^
/builds/isc-projects/bind9/lib/isc/include/isc/buffer.h:821:16: note: expanded from macro 'ISC__BUFFER_AVAILABLEREGION'
                (_r)->base = isc_buffer_used(_b);              \
                             ^~~~~~~~~~~~~~~~~~~
/builds/isc-projects/bind9/lib/isc/include/isc/buffer.h:152:29: note: expanded from macro 'isc_buffer_used'
        ((void *)((unsigned char *)(b)->base + (b)->used)) /*d*/
                                   ^~~~~~~~~
1 warning generated.

--

./main.c:1254:9: warning: Access to field 'sctx' results in a dereference of a null pointer (loaded from variable 'named_g_server')
        sctx = named_g_server->sctx;
               ^~~~~~~~~~~~~~~~~~~~
1 warning generated.

References:
1. https://clang-analyzer.llvm.org/faq.html#null_pointer
This commit is contained in:
Ondřej Surý 2020-03-25 17:25:45 +01:00
parent e3acfedbe3
commit f3ba17fedc
2 changed files with 5 additions and 0 deletions
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4
bin/dnssec/dnssec-cds.c
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@ -788,6 +788,8 @@ ds_from_cds(dns_rdatalist_t *dslist, isc_buffer_t *buf, dns_rdata_t *cds) {
dns_rdata_ds_t ds;
dns_rdata_t *rdata;
REQUIRE(buf != NULL);
rdata = rdata_get();
result = dns_rdata_tostruct(cds, &ds, NULL);
@ -807,6 +809,8 @@ ds_from_cdnskey(dns_rdatalist_t *dslist, isc_buffer_t *buf,
isc_result_t result;
unsigned i, n;
REQUIRE(buf != NULL);
n = sizeof(dtype)/sizeof(dtype[0]);
for (i = 0; i < n; i++) {
if (dtype[i] != 0) {

1
bin/named/main.c
View file

@ -1229,6 +1229,7 @@ setup(void) {
#endif
named_server_create(named_g_mctx, &named_g_server);
ENSURE(named_g_server != NULL);
sctx = named_g_server->sctx;
/*