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Fix overflow in lto-partition.c
- From: Jan Hubicka <hubicka at ucw dot cz>
- To: gcc-patches at gcc dot gnu dot org
- Date: Fri, 23 Feb 2018 19:19:41 +0100
- Subject: Fix overflow in lto-partition.c
- Authentication-results: sourceware.org; auth=none
Hi,
this patch fixes fork bomb gcc turns into when you compile firefox with LTO and
profile feedback. We put partition size to INT_MAX to avoid creation of new
partition but because we compute partition_size * 3 / 2 we end up with negative
bound and producing individual partition for every new symbol.
Bootstrapped/regtested x86_64-linux, commited
We ought to backport this to all release branches.
Honza
Index: ChangeLog
===================================================================
--- ChangeLog (revision 257938)
+++ ChangeLog (working copy)
@@ -1,5 +1,9 @@
2018-02-08 Jan Hubicka <hubicka@ucw.cz>
+ * lto-partition.c (lto_balanced_map): Watch overflow.
+
+2018-02-08 Jan Hubicka <hubicka@ucw.cz>
+
PR ipa/81360
* lto.c (unify_scc): Register prevailing trees, not trees to be freed.
(read_cgraph_and_symbols): Use
Index: lto-partition.c
===================================================================
--- lto-partition.c (revision 257938)
+++ lto-partition.c (working copy)
@@ -757,7 +757,8 @@ lto_balanced_map (int n_lto_partitions,
if (npartitions < n_lto_partitions)
partition_size = total_size / (n_lto_partitions - npartitions);
else
- partition_size = INT_MAX;
+ /* Watch for overflow. */
+ partition_size = INT_MAX / 16;
if (partition_size < PARAM_VALUE (MIN_PARTITION_SIZE))
partition_size = PARAM_VALUE (MIN_PARTITION_SIZE);