[reactos] 02/03: [RTL] RtlDefaultNpAcl(): Don't hardcode SidBuffer size, but deduce it through FIELD_OFFSETs.

[Hermès Bélusca-Maïto]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=671d7e4741b71c39f7365…

commit 671d7e4741b71c39f736576342ecd577da2fe223
Author:     Hermès Bélusca-Maïto <hermes.belusca-maito(a)reactos.org>
AuthorDate: Sun Oct 30 19:37:52 2022 +0100
Commit:     Hermès Bélusca-Maïto <hermes.belusca-maito(a)reactos.org>
CommitDate: Thu Nov 3 02:50:21 2022 +0100

    [RTL] RtlDefaultNpAcl(): Don't hardcode SidBuffer size, but deduce it through
FIELD_OFFSETs.
---
 sdk/lib/rtl/security.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/sdk/lib/rtl/security.c b/sdk/lib/rtl/security.c
index c2f5deebfc8..564bf24de61 100644
--- a/sdk/lib/rtl/security.c
+++ b/sdk/lib/rtl/security.c
@@ -245,14 +245,17 @@ RtlDefaultNpAcl(OUT PACL *pAcl)
     SID_IDENTIFIER_AUTHORITY NtAuthority    = {SECURITY_NT_AUTHORITY};
     SID_IDENTIFIER_AUTHORITY WorldAuthority = {SECURITY_WORLD_SID_AUTHORITY};
 
+    C_ASSERT(sizeof(ACE) == FIELD_OFFSET(ACCESS_ALLOWED_ACE, SidStart));
+
     /*
      * Temporary buffer large enough to hold a maximum of two SIDs.
      * An alternative is to call RtlAllocateAndInitializeSid many times...
      */
-    UCHAR SidBuffer[16];
+    UCHAR SidBuffer[FIELD_OFFSET(SID, SubAuthority)
+                    + 2*RTL_FIELD_SIZE(SID, SubAuthority)];
     PSID Sid = (PSID)&SidBuffer;
 
-    ASSERT(RtlLengthRequiredSid(2) == 16);
+    ASSERT(RtlLengthRequiredSid(2) == sizeof(SidBuffer));
 
     /* Initialize the user ACL pointer */
     *pAcl = NULL;
@@ -309,12 +312,9 @@ RtlDefaultNpAcl(OUT PACL *pAcl)
 
     /*
      * Allocate one ACL with 5 ACEs.
-     *
-     * NOTE: sizeof(ACE) == sizeof(ACCESS_ALLOWED_ACE) -
sizeof(((ACCESS_ALLOWED_ACE*)NULL)->SidStart)
-     * (see kernel32/client/debugger.c line 54).
      */
     AclSize = sizeof(ACL) +                     // Header
-              5 * sizeof(ACE /*ACCESS_ALLOWED_ACE*/) +  // 5 ACEs:
+              5 * sizeof(ACE) +                 // 5 ACEs:
               RtlLengthRequiredSid(1) +         // LocalSystem
               RtlLengthRequiredSid(2) +         // Administrators
               RtlLengthRequiredSid(1) +         // Anonymous
@@ -672,7 +672,7 @@ RtlNewSecurityGrantedAccess(IN ACCESS_MASK DesiredAccess,
         return STATUS_BUFFER_TOO_SMALL;
     }
 
-    /* Check if the SACL right was granted... */
+    /* Check if the SACL right was granted */
     RtlZeroMemory(Privileges, Size);
     if (Granted)
     {