[PATCH AUTOSEL 6.18-6.1] smb/client: fix NT_STATUS_UNABLE_TO_FREE_VM value

[Sasha Levin <sashal@kernel.org>]

From: ChenXiaoSong <chenxiaosong@kylinos.cn>

[ Upstream commit 9f99caa8950a76f560a90074e3a4b93cfa8b3d84 ]

This was reported by the KUnit tests in the later patches.

See MS-ERREF 2.3.1 STATUS_UNABLE_TO_FREE_VM. Keep it consistent with the
value in the documentation.

Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

LLM Generated explanations, may be completely bogus:

## Analysis of smb/client: fix NT_STATUS_UNABLE_TO_FREE_VM value

### 1. COMMIT MESSAGE ANALYSIS

The commit explicitly states it's a "fix" for an incorrect NT status
code value. Key points:
- Found by KUnit tests (systematic testing uncovered the issue)
- References MS-ERREF 2.3.1 documentation as the authoritative source
- Acked by Paulo Alcantara (Red Hat) - a key SMB/CIFS maintainer
- Committed by Steve French - the SMB subsystem maintainer

### 2. CODE CHANGE ANALYSIS

The change is a single-line modification in `fs/smb/client/nterr.h`:

```c
-#define NT_STATUS_UNABLE_TO_FREE_VM 0x80000000 | 0x001a
+#define NT_STATUS_UNABLE_TO_FREE_VM 0xC0000000 | 0x001a
```

In NT status codes, the high bits encode severity:
- `0x00000000` = Success
- `0x40000000` = Informational
- `0x80000000` = Warning
- `0xC0000000` = Error

The bug: `NT_STATUS_UNABLE_TO_FREE_VM` was incorrectly defined as a
"Warning" (`0x80000000`) instead of "Error" (`0xC0000000`). Looking at
the context, **all surrounding status codes** use `0xC0000000`, making
this one obvious outlier.

Per Microsoft's MS-ERREF documentation, STATUS_UNABLE_TO_FREE_VM
(0xC000001A) is indeed an error status, not a warning.

### 3. CLASSIFICATION

- **Bug type:** Incorrect constant value (data bug)
- **Not a feature:** Simply corrects an existing definition to match
  specification
- **Not a security issue:** Though incorrect error handling could have
  unexpected effects

### 4. SCOPE AND RISK ASSESSMENT

- **Lines changed:** 1
- **Files touched:** 1 (header file)
- **Complexity:** Minimal - single character change (`8` → `C`)
- **Risk:** Essentially zero - corrects an obvious typo/error to match:
  1. The official Microsoft documentation
  2. The pattern used by all surrounding definitions

### 5. USER IMPACT

If an SMB server returns this status code, the client would fail to
properly match and handle it due to the incorrect value. This could
cause:
- Failure to recognize error conditions
- Incorrect error messages to users
- Potential mishandling of this error scenario

While this specific status code may be rarely encountered in practice,
when it does occur, the current code would misbehave.

### 6. STABILITY INDICATORS

- **Reviewed by maintainers:** Acked by Paulo Alcantara, committed by
  Steve French
- **Testing:** Found through KUnit tests (automated testing)
- **Pattern consistency:** All other NT_STATUS_* codes in the same
  numerical range use `0xC0000000`

### 7. DEPENDENCY CHECK

This is a completely standalone fix. The header file has existed for a
long time, and this is just correcting an incorrect value within it. No
dependencies on other commits.

---

### Summary

**Should this be backported?**

This commit is an excellent backport candidate:

1. **Obviously correct:** The fix makes the value match both official
   Microsoft documentation and the pattern used by all surrounding
   definitions
2. **Fixes a real bug:** Incorrect status code would cause mismatched
   error handling
3. **Minimal scope:** One-character change in a single header file
4. **Zero regression risk:** This is purely a correctness fix to a
   constant
5. **No new features:** Just corrects existing code
6. **No dependencies:** Standalone fix
7. **Well-reviewed:** Acked by key SMB maintainer

This is exactly the type of safe, surgical, low-risk fix that stable
trees should include. The change is so minimal and so obviously correct
that there's essentially no risk, while the benefit is ensuring correct
SMB protocol handling.

**YES**

 fs/smb/client/nterr.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/smb/client/nterr.h b/fs/smb/client/nterr.h
index 180602c22355e..e3a607b45e719 100644
--- a/fs/smb/client/nterr.h
+++ b/fs/smb/client/nterr.h
@@ -70,7 +70,7 @@ extern const struct nt_err_code_struct nt_errs[];
 #define NT_STATUS_NO_MEMORY 0xC0000000 | 0x0017
 #define NT_STATUS_CONFLICTING_ADDRESSES 0xC0000000 | 0x0018
 #define NT_STATUS_NOT_MAPPED_VIEW 0xC0000000 | 0x0019
-#define NT_STATUS_UNABLE_TO_FREE_VM 0x80000000 | 0x001a
+#define NT_STATUS_UNABLE_TO_FREE_VM 0xC0000000 | 0x001a
 #define NT_STATUS_UNABLE_TO_DELETE_SECTION 0xC0000000 | 0x001b
 #define NT_STATUS_INVALID_SYSTEM_SERVICE 0xC0000000 | 0x001c
 #define NT_STATUS_ILLEGAL_INSTRUCTION 0xC0000000 | 0x001d
-- 
2.51.0