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Message-ID: <CAMKF1sphZAsqVQE7XWnnnORTRV9FE3h0SZgQVsXQ8z12Ee6sbg@mail.gmail.com>
Date: Sun, 31 Jan 2016 08:04:45 -0800
From: Khem Raj <raj.khem@...il.com>
To: musl@...ts.openwall.com
Subject: Re: [PATCH] regex: increase the stack tre uses for tnfa creation
On Sun, Jan 31, 2016 at 7:46 AM, Szabolcs Nagy <nsz@...t70.net> wrote:
> 10k elements stack is increased to 1000k,
It seems this stack is on heap is that right ?
if not then does this enforce some higher minimum limit on stack
otherwise tnfa creation fails
> for reasonable sized patterns: a single literal char can add 7 elements
> to this stack, so regcomp of an 1500 char long pattern (with only litral
> chars) fails with REG_ESPACE. (the new limit allows about < 150k chars,
> this arbitrary limit allows most command line regex usage.)
>
> ideally there would be no upper bound: regcomp dynamically reallocates
> this buffer, every reallocation checks for allocation failure and at
> the end this stack is freed so there is no reason for special bound.
> however that may have unwanted effect on regcomp and regexec runtime
> so this is a conservative change.
> ---
> src/regex/regcomp.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/regex/regcomp.c b/src/regex/regcomp.c
> index 7ce2988..da6abd1 100644
> --- a/src/regex/regcomp.c
> +++ b/src/regex/regcomp.c
> @@ -2688,7 +2688,7 @@ regcomp(regex_t *restrict preg, const char *restrict regex, int cflags)
>
> /* Allocate a stack used throughout the compilation process for various
> purposes. */
> - stack = tre_stack_new(512, 10240, 128);
> + stack = tre_stack_new(512, 1024000, 128);
> if (!stack)
> return REG_ESPACE;
> /* Allocate a fast memory allocator. */
> --
> 2.7.0
>
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