[TEXTSEARCH]: Fix Boyer Moore initialization bug

[TEXTSEARCH]: Fix Boyer Moore initialization bug

[Patrick McHardy]

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Hi Dave,

this fixes an initialization bug in the bm textsearch
algorithm affecting the netfilter string match (the
only user AFAIK). Please apply to 2.6.18, thanks.

@stable maintainers: the bm_ts author asked me to also
submit this to -stable, please apply.


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[TEXTSEARCH]: Fix Boyer Moore initialization bug

The pattern is set after trying to compute the prefix table, which tries
to use it. Initialize it before calling compute_prefix_tbl, make
compute_prefix_tbl consistently use only the data from struct ts_bm
and remove the now unnecessary arguments.

Signed-off-by: Michael Rash <mbr@cipherdyne.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>

---
commit 96d2404fab775fc7aebf06956bd3ea5e8996b0f7
tree 682dee25bd20e0d85f909fbf5967db2844d58253
parent 8ebd6bb0f469f2759f39e73adee6916a3d975393
author Michael Rash <mbr@cipherdyne.org> Thu, 17 Aug 2006 17:43:21 +0200
committer Patrick McHardy <kaber@trash.net> Thu, 17 Aug 2006 17:43:21 +0200

 lib/ts_bm.c |   11 +++++------
 1 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/lib/ts_bm.c b/lib/ts_bm.c
index 0110e44..d90822c 100644
--- a/lib/ts_bm.c
+++ b/lib/ts_bm.c
@@ -111,15 +111,14 @@ static int subpattern(u8 *pattern, int i
 	return ret;
 }
 
-static void compute_prefix_tbl(struct ts_bm *bm, const u8 *pattern,
-			       unsigned int len)
+static void compute_prefix_tbl(struct ts_bm *bm)
 {
 	int i, j, g;
 
 	for (i = 0; i < ASIZE; i++)
-		bm->bad_shift[i] = len;
-	for (i = 0; i < len - 1; i++)
-		bm->bad_shift[pattern[i]] = len - 1 - i;
+		bm->bad_shift[i] = bm->patlen;
+	for (i = 0; i < bm->patlen - 1; i++)
+		bm->bad_shift[bm->pattern[i]] = bm->patlen - 1 - i;
 
 	/* Compute the good shift array, used to match reocurrences 
 	 * of a subpattern */
@@ -150,8 +149,8 @@ static struct ts_config *bm_init(const v
 	bm = ts_config_priv(conf);
 	bm->patlen = len;
 	bm->pattern = (u8 *) bm->good_shift + prefix_tbl_len;
-	compute_prefix_tbl(bm, pattern, len);
 	memcpy(bm->pattern, pattern, len);
+	compute_prefix_tbl(bm);
 
 	return conf;
 }

Re: [TEXTSEARCH]: Fix Boyer Moore initialization bug

[David Miller]

From: Patrick McHardy <kaber@trash.net>
Date: Tue, 22 Aug 2006 04:07:57 +0200

> this fixes an initialization bug in the bm textsearch
> algorithm affecting the netfilter string match (the
> only user AFAIK). Please apply to 2.6.18, thanks.
> 
> @stable maintainers: the bm_ts author asked me to also
> submit this to -stable, please apply.

Applied and Ack'd for -stable.

Re: [stable] [TEXTSEARCH]: Fix Boyer Moore initialization bug

[Greg KH]

On Tue, Aug 22, 2006 at 12:45:34AM -0700, David Miller wrote:
> From: Patrick McHardy <kaber@trash.net>
> Date: Tue, 22 Aug 2006 04:07:57 +0200
> 
> > this fixes an initialization bug in the bm textsearch
> > algorithm affecting the netfilter string match (the
> > only user AFAIK). Please apply to 2.6.18, thanks.
> > 
> > @stable maintainers: the bm_ts author asked me to also
> > submit this to -stable, please apply.
> 
> Applied and Ack'd for -stable.

Queued to -stable, thanks.

greg k-h

Re: [TEXTSEARCH]: Fix Boyer Moore initialization bug

[Adrian Bunk]

On Tue, Aug 22, 2006 at 12:45:34AM -0700, David Miller wrote:
> From: Patrick McHardy <kaber@trash.net>
> Date: Tue, 22 Aug 2006 04:07:57 +0200
> 
> > this fixes an initialization bug in the bm textsearch
> > algorithm affecting the netfilter string match (the
> > only user AFAIK). Please apply to 2.6.18, thanks.
> > 
> > @stable maintainers: the bm_ts author asked me to also
> > submit this to -stable, please apply.
> 
> Applied and Ack'd for -stable.

Thanks, applied to 2.6.16.

cu
Adrian

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       "Only a promise," Lao Er said.
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