Bug #19773: Intermittent SIGSEGV during marking of Ripper parser

• Status: Closed
• Assignee: -
• Target version: -
• Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN

[eightbitraptor (Matt V-H)]

Github PR 8089

Intermittent SIGSEGV during marking of the Ripper parser. A failing build can be seen on ci.rvm.jp (build 4643684).

Inside ripper_s_allocate first we use TypedData_Make_Struct to create a new T_DATA object in the Ruby heap. This allocates an empty struct (struct ripper). Further down the function we allocate another struct (struct parser_params during rb_ruby_ripper_parser_allcoate) and assign it to a pointer from the first struct, which is attached to the T_DATA object.

rb_ruby_ripper_parser_allocate can trigger GC, as it uses ruby_xcalloc. But if GC is triggered at this point then the parser_params have not been allocated yet, and so the struct ripper contains a NULL reference.

This causes a SEGV when we try and mark the T_DATA wrapper around the struct ripper.

This can be replicated locally using the following test script

require "ripper"
GC.stress = true
Ripper.new

[eightbitraptor (Matt V-H)]

• Description updated (diff)

[eightbitraptor (Matt V-H)]

It looks like 3 of us have independently fixed this issue (in #8084, #8085, and #8089).

Nobu's fix in 8085 has already been merged so I'm closing this ticket.

[eightbitraptor (Matt V-H)]

• Status changed from Open to Closed