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authorWilco Dijkstra <wdijkstr@arm.com>2019-05-10 16:38:21 +0100
committerWilco Dijkstra <wdijkstr@arm.com>2019-05-10 16:38:21 +0100
commit5ad533e8e65092be962e414e0417112c65d154fb (patch)
treebb926e04c328e70f54fc026cbee805c52d9b2f6d /manual
parentsem_close: Use __twalk_r (diff)
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Fix tcache count maximum (BZ #24531)
The tcache counts[] array is a char, which has a very small range and thus may overflow. When setting tcache_count tunable, there is no overflow check. However the tunable must not be larger than the maximum value of the tcache counts[] array, otherwise it can overflow when filling the tcache. [BZ #24531] * malloc/malloc.c (MAX_TCACHE_COUNT): New define. (do_set_tcache_count): Only update if count is small enough. * manual/tunables.texi (glibc.malloc.tcache_count): Document max value.
Diffstat (limited to 'manual')
-rw-r--r--manual/tunables.texi4
1 files changed, 2 insertions, 2 deletions
diff --git a/manual/tunables.texi b/manual/tunables.texi
index 749cabff1b..ae638823a2 100644
--- a/manual/tunables.texi
+++ b/manual/tunables.texi
@@ -189,8 +189,8 @@ per-thread cache. The default (and maximum) value is 1032 bytes on
@deftp Tunable glibc.malloc.tcache_count
The maximum number of chunks of each size to cache. The default is 7.
-There is no upper limit, other than available system memory. If set
-to zero, the per-thread cache is effectively disabled.
+The upper limit is 127. If set to zero, the per-thread cache is effectively
+disabled.
The approximate maximum overhead of the per-thread cache is thus equal
to the number of bins times the chunk count in each bin times the size