…y after releasing the mutex that guards it

32a9f13 wallet: avoid returning a reference to vMasterKey after releasing the mutex that guards it (Vasil Dimov)

Pull request description:

  `CWallet::GetEncryptionKey()` would return a reference to the internal
  `CWallet::vMasterKey`, guarded by `CWallet::cs_wallet`, which is unsafe.

  Returning a copy would be a shorter solution, but could have security
  implications of the master key remaining somewhere in the memory even
  after `CWallet::Lock()` (the current calls to
  `CWallet::GetEncryptionKey()` are safe, but that is not future proof).

  So, instead of `EncryptSecret(m_storage.GetEncryptionKey(), ...)`
  change the `GetEncryptionKey()` method to provide the encryption
  key to a given callback:
  `m_storage.WithEncryptionKey([](const CKeyingMaterial& k) { EncryptSecret(k, ...); })`

  This silences the following (clang 18):

  ```
  wallet/wallet.cpp:3520:12: error: returning variable 'vMasterKey' by reference requires holding mutex 'cs_wallet' [-Werror,-Wthread-safety-reference-return]
   3520 |     return vMasterKey;
        |            ^
  ```

  ---
  _Previously this PR modified both ArgsManager and wallet code. But the ArgsManager commit bitcoin@856c887 was merged in bitcoin#29040 so now this only affects wallet code. The previous PR description was:_

  Avoid this unsafe pattern from `ArgsManager` and `CWallet`:

  ```cpp
  class A
  {
      Mutex mutex;
      Foo member GUARDED_BY(mutex);
      const Foo& Get()
      {
          LOCK(mutex);
          return member;
      } // callers of `Get()` will have access to `member` without owning the mutex.
  ```

ACKs for top commit:
  achow101:
    ACK 32a9f13
  ryanofsky:
    Code review ACK 32a9f13. This seems like a potentially real race condition, and the fix here is pretty simple.
  furszy:
    ACK 32a9f13

Tree-SHA512: 133da84691642afc1a73cf14ad004a7266cb4be1a6a3ec634d131dca5dbcdef52522c1d5eb04f5b6c4e06e1fc3e6ac57315f8fe1e207b464ca025c2b4edefdc1

…itcoin#28774 - lock annotations

1db9e6a Merge bitcoin#19979: Replace LockAssertion with AssertLockHeld, remove LockAssertion (MarcoFalke)
d0a4198 Merge bitcoin#21598: refactor: Remove negative lock annotations from globals (MarcoFalke)
55114a6 Merge bitcoin#19668: Do not hide compile-time thread safety warnings (MarcoFalke)
898282d Merge bitcoin#28774: wallet: avoid returning a reference to vMasterKey after releasing the mutex that guards it (Ava Chow)
6d45284 fix: add missing lock annotation for ContextualCheckBlock and related TODO (Konstantin Akimov)
846ebab fix: fixes for orphange's locks and cs_main (Konstantin Akimov)
002580c fix: add ignoring safety-annotation for llmq/signing_shares due to template lambdas (Konstantin Akimov)
502d6ae fix: add multiple missing annotation about locks for dash specific code (Konstantin Akimov)
a219a8b partial Merge bitcoin#29040: refactor: Remove pre-C++20 code, fs::path cleanup (Konstantin Akimov)
042e8a4 fix: drop unneded lock assert in net.cpp for m_nodes_mutex (Konstantin Akimov)

Pull request description:

  ## What was done?
  These 4 backports improve noticeable implementation of thread-safety analysis by moving many possible warnings to compilation level.
  There's a lot of fixes for annotations after that!

  ## How Has This Been Tested?
  Build with clang:
  ```
  CC=clang CXX=clang++ ./configure --prefix=$(pwd)/depends/x86_64-pc-linux-gnu --enable-suppress-external-warnings   --enable-debug  --enable-stacktraces --enable-werror --enable-crash-hooks --enable-maintainer-mode
  ```

  ## Breaking Changes
  n/a

  ## Checklist:
  - [x] I have performed a self-review of my own code
  - [x] I have commented my code, particularly in hard-to-understand areas
  - [x] I have added or updated relevant unit/integration/functional/e2e tests
  - [x] I have made corresponding changes to the documentation
  - [x] I have assigned this pull request to a milestone

ACKs for top commit:
  UdjinM6:
    utACK 1db9e6a
  PastaPastaPasta:
    utACK 1db9e6a

Tree-SHA512: 42a73e423f311689babc366b58a92f024556cf63af93357cfa0715c471efc1491d02ed9e7ba19b23efcdf423ab5bd051a24da2ad64c32e4b6db132a05f6669c1

… mutex that guards it

Summary:
```
`CWallet::GetEncryptionKey()` would return a reference to the internal
`CWallet::vMasterKey`, guarded by `CWallet::cs_wallet`, which is unsafe.

Returning a copy would be a shorter solution, but could have security
implications of the master key remaining somewhere in the memory even
after `CWallet::Lock()` (the current calls to
`CWallet::GetEncryptionKey()` are safe, but that is not future proof).

So, instead of `EncryptSecret(m_storage.GetEncryptionKey(), ...)`
change the `GetEncryptionKey()` method to provide the encryption
key to a given callback:
`m_storage.WithEncryptionKey([](const CKeyingMaterial& k) { EncryptSecret(k, ...); })`

This silences the following (clang 18):

wallet/wallet.cpp:3520:12: error: returning variable 'vMasterKey' by reference requires holding mutex 'cs_wallet' [-Werror,-Wthread-safety-reference-return]
 3520 |     return vMasterKey;
      |            ^
```

Backport of [[bitcoin/bitcoin#28774 | core#28774]].

Test Plan:
With clang 18:
  ninja all check-all

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D17013

… mutex that guards it

Summary:
```
`CWallet::GetEncryptionKey()` would return a reference to the internal
`CWallet::vMasterKey`, guarded by `CWallet::cs_wallet`, which is unsafe.

Returning a copy would be a shorter solution, but could have security
implications of the master key remaining somewhere in the memory even
after `CWallet::Lock()` (the current calls to
`CWallet::GetEncryptionKey()` are safe, but that is not future proof).

So, instead of `EncryptSecret(m_storage.GetEncryptionKey(), ...)`
change the `GetEncryptionKey()` method to provide the encryption
key to a given callback:
`m_storage.WithEncryptionKey([](const CKeyingMaterial& k) { EncryptSecret(k, ...); })`

This silences the following (clang 18):

wallet/wallet.cpp:3520:12: error: returning variable 'vMasterKey' by reference requires holding mutex 'cs_wallet' [-Werror,-Wthread-safety-reference-return]
 3520 |     return vMasterKey;
      |            ^
```

Backport of [[bitcoin/bitcoin#28774 | core#28774]].

Test Plan:
With clang 18:
  ninja all check-all

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D17013