MDEV-35646: Limit pseudo_thread_id to UINT32_MAX

Although the `my_thread_id` type is 64 bits, binlog format specs limits it to 32 bits in practice. (See also: MDEV-35706) The writable SQL variable `pseudo_thread_id` didn’t realize this though and had a range of `ULONGLONG_MAX` (at least `UINT64_MAX` in C/C++). It consequentially accepted larger values silently, but only the lower 32 bits of whom gets binlogged; this could lead to inconsistency. Reviewed-by: Brandon Nesterenko <[email protected]>
MariaDB · Jan 14, 2025 · 1d0368d · 1d0368d
1 parent 4b0ac5a
commit 1d0368d
Show file tree

Hide file tree

Showing 5 changed files with 10 additions and 4 deletions.
diff --git a/include/my_pthread.h b/include/my_pthread.h
@@ -641,6 +641,12 @@ extern pthread_mutexattr_t my_errorcheck_mutexattr;
 #endif
 
 typedef uint64 my_thread_id;
+/**
+  The binary log format limits `my_thread_id` to 32 bits in practice (though
+  not all `thread_id`s are typed as such, including @ref my_thread_id itself).
+  @see MDEV-35706
+*/
+#define MY_THREAD_ID_MAX UINT32_MAX
 
 extern void my_threadattr_global_init(void);
 extern my_bool my_thread_global_init(void);

diff --git a/mysql-test/suite/sys_vars/r/sysvars_server_embedded.result b/mysql-test/suite/sys_vars/r/sysvars_server_embedded.result
@@ -2877,7 +2877,7 @@ VARIABLE_SCOPE	SESSION ONLY
 VARIABLE_TYPE	BIGINT UNSIGNED
 VARIABLE_COMMENT	This variable is for internal server use
 NUMERIC_MIN_VALUE	0
-NUMERIC_MAX_VALUE	18446744073709551615
+NUMERIC_MAX_VALUE	4294967295
 NUMERIC_BLOCK_SIZE	1
 ENUM_VALUE_LIST	NULL
 READ_ONLY	NO

diff --git a/mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result b/mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result
@@ -3037,7 +3037,7 @@ VARIABLE_SCOPE	SESSION ONLY
 VARIABLE_TYPE	BIGINT UNSIGNED
 VARIABLE_COMMENT	This variable is for internal server use
 NUMERIC_MIN_VALUE	0
-NUMERIC_MAX_VALUE	18446744073709551615
+NUMERIC_MAX_VALUE	4294967295
 NUMERIC_BLOCK_SIZE	1
 ENUM_VALUE_LIST	NULL
 READ_ONLY	NO

diff --git a/sql/mysqld.cc b/sql/mysqld.cc
@@ -9778,7 +9778,7 @@ void init_server_psi_keys(void)
 
 */
 
-static my_thread_id thread_id_max= UINT_MAX32;
+static my_thread_id thread_id_max= MY_THREAD_ID_MAX;
 
 #include <vector>
 #include <algorithm>

diff --git a/sql/sys_vars.cc b/sql/sys_vars.cc
@@ -1767,7 +1767,7 @@ Sys_pseudo_thread_id(
        "pseudo_thread_id",
        "This variable is for internal server use",
        SESSION_ONLY(pseudo_thread_id),
-       NO_CMD_LINE, VALID_RANGE(0, ULONGLONG_MAX), DEFAULT(0),
+       NO_CMD_LINE, VALID_RANGE(0, MY_THREAD_ID_MAX), DEFAULT(0),
        BLOCK_SIZE(1), NO_MUTEX_GUARD, IN_BINLOG);
 
 static bool