From 009d71409821a6ac4f1b32aaae2c856c20a29f92 Mon Sep 17 00:00:00 2001 From: Keith Randall Date: Thu, 22 Oct 2020 16:37:19 -0700 Subject: cmd/compile, runtime: store pointers to go:notinheap types indirectly pointers to go:notinheap types should be treated as scalars. That means they shouldn't be stored directly in interfaces, or directly in reflect.Value.ptr. Also be sure to use uintpr to compare such pointers in reflect.DeepEqual. Fixes #42076 Change-Id: I53735f6d434e9c3108d4940bd1bae14c61ef2a74 Reviewed-on: https://go-review.googlesource.com/c/go/+/264480 Trust: Keith Randall Reviewed-by: Ian Lance Taylor --- src/runtime/netpoll.go | 47 +++++++++++++++++++++++++++++++++-------------- 1 file changed, 33 insertions(+), 14 deletions(-) (limited to 'src/runtime/netpoll.go') diff --git a/src/runtime/netpoll.go b/src/runtime/netpoll.go index 34ea82a7fa..77eb3aa4c6 100644 --- a/src/runtime/netpoll.go +++ b/src/runtime/netpoll.go @@ -79,16 +79,17 @@ type pollDesc struct { lock mutex // protects the following fields fd uintptr closing bool - everr bool // marks event scanning error happened - user uint32 // user settable cookie - rseq uintptr // protects from stale read timers - rg uintptr // pdReady, pdWait, G waiting for read or nil - rt timer // read deadline timer (set if rt.f != nil) - rd int64 // read deadline - wseq uintptr // protects from stale write timers - wg uintptr // pdReady, pdWait, G waiting for write or nil - wt timer // write deadline timer - wd int64 // write deadline + everr bool // marks event scanning error happened + user uint32 // user settable cookie + rseq uintptr // protects from stale read timers + rg uintptr // pdReady, pdWait, G waiting for read or nil + rt timer // read deadline timer (set if rt.f != nil) + rd int64 // read deadline + wseq uintptr // protects from stale write timers + wg uintptr // pdReady, pdWait, G waiting for write or nil + wt timer // write deadline timer + wd int64 // write deadline + self *pollDesc // storage for indirect interface. See (*pollDesc).makeArg. } type pollCache struct { @@ -157,6 +158,7 @@ func poll_runtime_pollOpen(fd uintptr) (*pollDesc, int) { pd.wseq++ pd.wg = 0 pd.wd = 0 + pd.self = pd unlock(&pd.lock) var errno int32 @@ -271,14 +273,14 @@ func poll_runtime_pollSetDeadline(pd *pollDesc, d int64, mode int) { // Copy current seq into the timer arg. // Timer func will check the seq against current descriptor seq, // if they differ the descriptor was reused or timers were reset. - pd.rt.arg = pd + pd.rt.arg = pd.makeArg() pd.rt.seq = pd.rseq resettimer(&pd.rt, pd.rd) } } else if pd.rd != rd0 || combo != combo0 { pd.rseq++ // invalidate current timers if pd.rd > 0 { - modtimer(&pd.rt, pd.rd, 0, rtf, pd, pd.rseq) + modtimer(&pd.rt, pd.rd, 0, rtf, pd.makeArg(), pd.rseq) } else { deltimer(&pd.rt) pd.rt.f = nil @@ -287,14 +289,14 @@ func poll_runtime_pollSetDeadline(pd *pollDesc, d int64, mode int) { if pd.wt.f == nil { if pd.wd > 0 && !combo { pd.wt.f = netpollWriteDeadline - pd.wt.arg = pd + pd.wt.arg = pd.makeArg() pd.wt.seq = pd.wseq resettimer(&pd.wt, pd.wd) } } else if pd.wd != wd0 || combo != combo0 { pd.wseq++ // invalidate current timers if pd.wd > 0 && !combo { - modtimer(&pd.wt, pd.wd, 0, netpollWriteDeadline, pd, pd.wseq) + modtimer(&pd.wt, pd.wd, 0, netpollWriteDeadline, pd.makeArg(), pd.wseq) } else { deltimer(&pd.wt) pd.wt.f = nil @@ -547,3 +549,20 @@ func (c *pollCache) alloc() *pollDesc { unlock(&c.lock) return pd } + +// makeArg converts pd to an interface{}. +// makeArg does not do any allocation. Normally, such +// a conversion requires an allocation because pointers to +// go:notinheap types (which pollDesc is) must be stored +// in interfaces indirectly. See issue 42076. +func (pd *pollDesc) makeArg() (i interface{}) { + x := (*eface)(unsafe.Pointer(&i)) + x._type = pdType + x.data = unsafe.Pointer(&pd.self) + return +} + +var ( + pdEface interface{} = (*pollDesc)(nil) + pdType *_type = efaceOf(&pdEface)._type +) -- cgit v1.2.1