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From c5eed6e541fe27d9e9dfd31f42c43f4dfa1f486b Mon Sep 17 00:00:00 2001
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From: Yves Orton <demerphq@gmail.com>
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Date: Sat, 11 Jul 2020 09:26:21 +0200
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Subject: [PATCH] hv.c: add a guard clause to prevent the number of buckets in
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a hash from getting too large
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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This caps it at 1<<28 buckets, eg, ~268M. In theory without a guard clause like
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this we could grow to the point of possibly wrapping around in terms of size,
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not to mention being ridiculously wasteful of memory at larger sizes.
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Even this cap is probably too high. It should probably be something like 1<<24.
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Petr Písař: Ported to 5.32.1 from
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aae087f7cec022be14a17deb95cb2208e16b7891.
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Signed-off-by: Petr Písař <ppisar@redhat.com>
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---
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hv.c | 10 +++++++++-
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1 file changed, 9 insertions(+), 1 deletion(-)
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diff --git a/hv.c b/hv.c
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index eccae62..32dbd19 100644
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--- a/hv.c
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+++ b/hv.c
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@@ -38,7 +38,13 @@ holds the key and hash value.
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* NOTE if you change this formula so we split earlier than previously
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* you MUST change the logic in hv_ksplit()
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*/
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-#define DO_HSPLIT(xhv) ( ((xhv)->xhv_keys + ((xhv)->xhv_keys >> 1)) > (xhv)->xhv_max )
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+
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+/* MAX_BUCKET_MAX is the maximum max bucket index, at which point we stop growing the
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+ * number of buckets,
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+ */
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+#define MAX_BUCKET_MAX ((1<<26)-1)
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+#define DO_HSPLIT(xhv) ( ( ((xhv)->xhv_keys + ((xhv)->xhv_keys >> 1)) > (xhv)->xhv_max ) && \
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+ ((xhv)->xhv_max < MAX_BUCKET_MAX) )
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#define HV_FILL_THRESHOLD 31
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static const char S_strtab_error[]
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@@ -1426,6 +1432,8 @@ S_hsplit(pTHX_ HV *hv, STRLEN const oldsize, STRLEN newsize)
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);
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PERL_ARGS_ASSERT_HSPLIT;
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+ if (newsize > MAX_BUCKET_MAX+1)
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+ return;
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PL_nomemok = TRUE;
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Renew(a, PERL_HV_ARRAY_ALLOC_BYTES(newsize)
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--
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2.26.2
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