Server crashes while accessing context variables concurrently [CORE4616]

[firebird-issue-importer]

Submitted by: Yurij (yurij)

Crash happens when one thread executes RDB$SET_CONTEXT:

fb_inet_server!set_context
fb_inet_server!CALL_UDF<long>
fb_inet_server!invoke
fb_inet_server!FUN_evaluate
fb_inet_server!EVL_expr
fb_inet_server!EXE_assignment
fb_inet_server!EXE_looper
fb_inet_server!looper_seh
fb_inet_server!execute_looper
fb_inet_server!EXE_start
fb_inet_server!execute_triggers
fb_inet_server!EXE_execute_db_triggers
fb_inet_server!JRD_start_multiple
fb_inet_server!jrd8_start_transaction

and another one retrieves the list of context variables due to the MON$ table request:

fb_inet_server!Jrd::DatabaseSnapshot::putContextVars+0xc3
fb_inet_server!Jrd::DatabaseSnapshot::dumpData+0x128
fb_inet_server!Jrd::DatabaseSnapshot::blockingAst+0x9c
fb_inet_server!Jrd::LockManager::blocking_action+0x134
fb_inet_server!Jrd::LockManager::signal_owner+0x37
fb_inet_server!Jrd::LockManager::post_blockage+0x1b4
fb_inet_server!Jrd::LockManager::wait_for_request+0x3d9
fb_inet_server!Jrd::LockManager::grant_or_que+0x8c
fb_inet_server!Jrd::LockManager::enqueue+0x20e
fb_inet_server!enqueue+0x51
fb_inet_server!LCK_lock+0x8f
fb_inet_server!LCK_lock_opt+0x36
fb_inet_server!lock_buffer+0xdb
fb_inet_server!CCH_fetch_lock+0x132
fb_inet_server!CCH_fetch+0x2d
fb_inet_server!DPM_gen_id+0x152

Bug is caused by the lack of proper synchronization inside RDB$SET_CONTEXT. v2.1 and v3 are not affected.

Commits: 0db9aff FirebirdSQL/fbt-repository@9db8123

====== Test Details ======

Can`t understand "pseudo-language" from starting post. Is it possible to write sequence of actions in each thread more simply ?

[firebird-issue-importer]

Modified by: @dyemanov

reporter: Dmitry Yemanov [ dimitr ] => Yurij [ yurij ]

assignee: Dmitry Yemanov [ dimitr ]

[firebird-issue-importer]

Modified by: @dyemanov

status: Open [ 1 ] => Resolved [ 5 ]

resolution: Fixed [ 1 ]

Fix Version: 2.5.4 [ 10585 ]

[firebird-issue-importer]

Modified by: @pavel-zotov

status: Resolved [ 5 ] => Resolved [ 5 ]

QA Status: Not enough information

Test Details: Can`t understand "pseudo-language" from starting post. Is it possible to write sequence of actions in each thread more simply ?

[firebird-issue-importer]

Modified by: @pcisar

status: Resolved [ 5 ] => Closed [ 6 ]