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bug#24751: 26.0.50; Regex stack overflow not detected properly (gets "Va
bug#24751: 26.0.50; Regex stack overflow not detected properly (gets "Variable binding depth exceeds max-specpdl-size")
Sun, 01 Jan 2017 13:33:35 -0500
Gnus/5.13 (Gnus v5.13) Emacs/25.1 (gnu/linux)
Eli Zaretskii <address@hidden> writes:
>> /* Define MATCH_MAY_ALLOCATE unless we need to make sure that the
>> searching and matching functions should not call alloca. On some
>> systems, alloca is implemented in terms of malloc, and if we're
>> using the relocating allocator routines, then malloc could cause a
>> relocation, which might (if the strings being searched are in the
>> ralloc heap) shift the data out from underneath the regexp
> The first part is not obsolete, but its reasoning is backwards:
> SAFE_ALLOCA indeed can call malloc, but it could only cause relocation
> if REGEX_MALLOC is defined (and ralloc.c is compiled in). And when
> you define REGEX_MALLOC, MATCH_MAY_ALLOCATE is undefined. So the text
> there should be revised.
Is there ever any case where REGEX_MALLOC is defined? I can't see where
it happens. I don't understand why you say relocation is dependent on
REGEX_MALLOC, I thought only REL_ALLOC affects that.
And since we added r_alloc_inhibit_buffer_relocation around the regex
calls, aren't all these concerns about relocation obsolete?
- bug#24751: 26.0.50; Regex stack overflow not detected properly (gets "Variable binding depth exceeds max-specpdl-size"),