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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=-1, RCVD_IN_MSPIKE_WL=-0.01, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 3/3/25 17:32, Peter Foley wrote: > The full output looks like: > > Uninitialized bytes in strlen at offset 0 inside [0xffffd1958110, 5) > ==9780==WARNING: MemorySanitizer: use-of-uninitialized-value > #0 0xaaaac1c4b170 in tdb_hash third_party/qemu/qobject/qdict.c:46:31 > #1 0xaaaac1c4b4a4 in qdict_get third_party/qemu/qobject/qdict.c:164:36 > #2 0xaaaac1c78468 in keyval_parse_put third_party/qemu/util/keyval.c:152:11 > #3 0xaaaac1c77740 in keyval_parse_one third_party/qemu/util/keyval.c:295:10 In order to get to if (!keyval_parse_put(cur, key_in_cur, qstring_from_gstring(val), key, key_end, errp)) { you must have gone through the only exit path of the earlier "for(;;)" loop: memcpy(key_in_cur, s, len); key_in_cur[len] = 0; s += len; if (*s != '.') { break; } meaning that key_in_cur is NULL-terminated and initialized---unless s is also uninitialized, but then adding an initializer would not do anything. Paolo > #4 0xaaaac1c77740 in keyval_parse_into third_party/qemu/util/keyval.c:530:13 > #5 0xaaaaba2f9524 in qemu_init third_party/qemu/system/vl.c:3322:21 > #6 0xaaaab9641c2c in main third_party/qemu/system/main.c:54:5 > #7 0xffffba320000 in __libc_start_main (/usr/grte/v5/lib64/libc.so.6+0x61000) (BuildId: 613d20d3b812b4c87fe9ebf8c4caae83) > #8 0xaaaab934bd10 in _start /usr/grte/v5/debug-src/src/csu/../sysdeps/aarch64/start.S:92 > > Uninitialized value was created by an allocation of 'key_in_cur.i' in the stack frame > #0 0xaaaac1c7708c in keyval_parse_one third_party/qemu/util/keyval.c:190:5 > #1 0xaaaac1c7708c in keyval_parse_into third_party/qemu/util/keyval.c:530:13 > > SUMMARY: MemorySanitizer: use-of-uninitialized-value third_party/qemu/qobject/qdict.c:46:31 in tdb_hash > Exiting > > > I don't have an easily shareable reproducer, but it's probably possible > to whip one up. > > > >> --- > >>  util/keyval.c | 2 +- > >>  1 file changed, 1 insertion(+), 1 deletion(-) > >> diff --git a/util/keyval.c b/util/keyval.c > >> index a70629a481..f33c64079d 100644 > >> --- a/util/keyval.c > >> +++ b/util/keyval.c > >> @@ -187,7 +187,7 @@ static const char *keyval_parse_one(QDict > *qdict, const char *params, > >>  { > >>      const char *key, *key_end, *val_end, *s, *end; > >>      size_t len; > >> -    char key_in_cur[128]; > >> +    char key_in_cur[128] = {}; > > Suspect overkill.  Would "" do? > > > It appears to resolve the complaint, yes.