From d231cb82494c59b7a5db0eb6304dcb5e5bce198f Mon Sep 17 00:00:00 2001 From: Austin Clements Date: Fri, 26 Jun 2015 17:24:12 -0400 Subject: [PATCH] runtime: repeat bitmap for slice of GCprog n-1 times, not n times Currently, to write out the bitmap of a slice of a type with a GCprog, we construct a new GCprog that executes the underlying type's GCprog to write out the bitmap once and then repeats those bits n more times. This results in n+1 repetitions of the bitmap, which is one more repetition than it should be. This corrupts the bitmap of the heap following the slice and may write past the mapped bitmap memory and segfault. Fix this by repeating the bitmap only n-1 more times. Fixes #11430. Change-Id: Ic24854363bffc5a755b66f257339f9309ada3aa5 Reviewed-on: https://go-review.googlesource.com/11570 Run-TryBot: Austin Clements Reviewed-by: Brad Fitzpatrick --- src/runtime/mbitmap.go | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/runtime/mbitmap.go b/src/runtime/mbitmap.go index efdcb8fca4..ef17409ebe 100644 --- a/src/runtime/mbitmap.go +++ b/src/runtime/mbitmap.go @@ -1193,7 +1193,7 @@ func heapBitsSetTypeGCProg(h heapBits, progSize, elemSize, dataSize, allocSize u } trailer[i] = byte(n) i++ - n = count + n = count - 1 for ; n >= 0x80; n >>= 7 { trailer[i] = byte(n | 0x80) i++ -- 2.50.0