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| author | Michael Anthony Knyszek <mknyszek@google.com> | 2023-11-15 21:54:45 +0000 |
|---|---|---|
| committer | Michael Knyszek <mknyszek@google.com> | 2023-11-16 05:48:17 +0000 |
| commit | 17eb0a2bac79eda8dc71d628474989d05d9755c5 (patch) | |
| tree | 12138930b91eb1100ec6075b4f5dd340d17a0f89 /src | |
| parent | 0011342590391655bd0cd732cf89c385c30c1278 (diff) | |
| download | go-17eb0a2bac79eda8dc71d628474989d05d9755c5.tar.xz | |
runtime: fix liveness issue in test-only getgcmask
getgcmask stops referencing the object passed to it sometime between
when the object is looked up and when the function returns. Notably,
this can happen while the GC mask is actively being produced, and thus
the GC might free the object.
This is easily reproducible by adding a runtime.GC call at just the
right place. Adding a KeepAlive on the heap-object path fixes it.
Fixes #64188.
Change-Id: I5ed4cae862fc780338b60d969fd7fbe896352ce4
Reviewed-on: https://go-review.googlesource.com/c/go/+/542716
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Diffstat (limited to 'src')
| -rw-r--r-- | src/runtime/mbitmap_allocheaders.go | 5 | ||||
| -rw-r--r-- | src/runtime/mbitmap_noallocheaders.go | 5 |
2 files changed, 10 insertions, 0 deletions
diff --git a/src/runtime/mbitmap_allocheaders.go b/src/runtime/mbitmap_allocheaders.go index 77f5b4c990..319d71f92f 100644 --- a/src/runtime/mbitmap_allocheaders.go +++ b/src/runtime/mbitmap_allocheaders.go @@ -1078,6 +1078,11 @@ func getgcmask(ep any) (mask []byte) { for len(mask) > 0 && mask[len(mask)-1] == 0 { mask = mask[:len(mask)-1] } + + // Make sure we keep ep alive. We may have stopped referencing + // ep's data pointer sometime before this point and it's possible + // for that memory to get freed. + KeepAlive(ep) return } diff --git a/src/runtime/mbitmap_noallocheaders.go b/src/runtime/mbitmap_noallocheaders.go index 96c70a0970..dab15889a4 100644 --- a/src/runtime/mbitmap_noallocheaders.go +++ b/src/runtime/mbitmap_noallocheaders.go @@ -744,6 +744,11 @@ func getgcmask(ep any) (mask []byte) { for len(mask) > 0 && mask[len(mask)-1] == 0 { mask = mask[:len(mask)-1] } + + // Make sure we keep ep alive. We may have stopped referencing + // ep's data pointer sometime before this point and it's possible + // for that memory to get freed. + KeepAlive(ep) return } |