From 1ba7341cb21d9edb2a04eb0b24b3af71899b35fc Mon Sep 17 00:00:00 2001 From: Cherry Mui Date: Wed, 21 Dec 2022 16:35:57 -0500 Subject: [PATCH] cmd/link, runtime: use a different section for Go libfuzzer counters Currently in libfuzzer mode, we put our counters in section __sancov_cntrs. When linking with C/C++ code that also has fuzzer counters, apparently the C linker combines our counters and their counters and registers them together. But in the Go runtime we also have code to register our counters. So the Go counters ended up registered twice, causing problems. Since we already have code to register our counters, put them in a Go-specific section so it won't be combined with the C counters. Fixes #57449. Change-Id: If3d41735124e7e301572d4b7aecf7d057ac134c0 Reviewed-on: https://go-review.googlesource.com/c/go/+/459055 Reviewed-by: Nicolas Hillegeer Reviewed-by: Than McIntosh TryBot-Result: Gopher Robot Run-TryBot: Cherry Mui --- src/cmd/link/internal/ld/data.go | 12 ++++++------ src/cmd/link/internal/ld/elf.go | 2 +- src/runtime/libfuzzer.go | 9 ++------- 3 files changed, 9 insertions(+), 14 deletions(-) diff --git a/src/cmd/link/internal/ld/data.go b/src/cmd/link/internal/ld/data.go index faae153babc899..94f8fc32d6e2d6 100644 --- a/src/cmd/link/internal/ld/data.go +++ b/src/cmd/link/internal/ld/data.go @@ -1860,9 +1860,9 @@ func (state *dodataState) allocateDataSections(ctxt *Link) { // Coverage instrumentation counters for libfuzzer. if len(state.data[sym.SLIBFUZZER_8BIT_COUNTER]) > 0 { - sect := state.allocateNamedSectionAndAssignSyms(&Segdata, "__sancov_cntrs", sym.SLIBFUZZER_8BIT_COUNTER, sym.Sxxx, 06) - ldr.SetSymSect(ldr.LookupOrCreateSym("__start___sancov_cntrs", 0), sect) - ldr.SetSymSect(ldr.LookupOrCreateSym("__stop___sancov_cntrs", 0), sect) + sect := state.allocateNamedSectionAndAssignSyms(&Segdata, ".go.fuzzcntrs", sym.SLIBFUZZER_8BIT_COUNTER, sym.Sxxx, 06) + ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.__start___sancov_cntrs", 0), sect) + ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.__stop___sancov_cntrs", 0), sect) ldr.SetSymSect(ldr.LookupOrCreateSym("internal/fuzz._counters", 0), sect) ldr.SetSymSect(ldr.LookupOrCreateSym("internal/fuzz._ecounters", 0), sect) } @@ -2643,7 +2643,7 @@ func (ctxt *Link) address() []*sym.Segment { bss = s case ".noptrbss": noptrbss = s - case "__sancov_cntrs": + case ".go.fuzzcntrs": fuzzCounters = s } } @@ -2764,8 +2764,8 @@ func (ctxt *Link) address() []*sym.Segment { ctxt.xdefine("runtime.end", sym.SBSS, int64(Segdata.Vaddr+Segdata.Length)) if fuzzCounters != nil { - ctxt.xdefine("__start___sancov_cntrs", sym.SLIBFUZZER_8BIT_COUNTER, int64(fuzzCounters.Vaddr)) - ctxt.xdefine("__stop___sancov_cntrs", sym.SLIBFUZZER_8BIT_COUNTER, int64(fuzzCounters.Vaddr+fuzzCounters.Length)) + ctxt.xdefine("runtime.__start___sancov_cntrs", sym.SLIBFUZZER_8BIT_COUNTER, int64(fuzzCounters.Vaddr)) + ctxt.xdefine("runtime.__stop___sancov_cntrs", sym.SLIBFUZZER_8BIT_COUNTER, int64(fuzzCounters.Vaddr+fuzzCounters.Length)) ctxt.xdefine("internal/fuzz._counters", sym.SLIBFUZZER_8BIT_COUNTER, int64(fuzzCounters.Vaddr)) ctxt.xdefine("internal/fuzz._ecounters", sym.SLIBFUZZER_8BIT_COUNTER, int64(fuzzCounters.Vaddr+fuzzCounters.Length)) } diff --git a/src/cmd/link/internal/ld/elf.go b/src/cmd/link/internal/ld/elf.go index 082adcc3c7f7a8..a1ae7eab57fe96 100644 --- a/src/cmd/link/internal/ld/elf.go +++ b/src/cmd/link/internal/ld/elf.go @@ -1371,7 +1371,7 @@ func (ctxt *Link) doelf() { shstrtab.Addstring(".data") shstrtab.Addstring(".bss") shstrtab.Addstring(".noptrbss") - shstrtab.Addstring("__sancov_cntrs") + shstrtab.Addstring(".go.fuzzcntrs") shstrtab.Addstring(".go.buildinfo") if ctxt.IsMIPS() { shstrtab.Addstring(".MIPS.abiflags") diff --git a/src/runtime/libfuzzer.go b/src/runtime/libfuzzer.go index 013e7165b21fff..0ece035405f7aa 100644 --- a/src/runtime/libfuzzer.go +++ b/src/runtime/libfuzzer.go @@ -148,13 +148,8 @@ var __sanitizer_cov_trace_const_cmp8 byte //go:cgo_import_static __sanitizer_cov_8bit_counters_init var __sanitizer_cov_8bit_counters_init byte -//go:linkname __start___sancov_cntrs __start___sancov_cntrs -//go:cgo_import_static __start___sancov_cntrs -var __start___sancov_cntrs byte - -//go:linkname __stop___sancov_cntrs __stop___sancov_cntrs -//go:cgo_import_static __stop___sancov_cntrs -var __stop___sancov_cntrs byte +// start, stop markers of counters, set by the linker +var __start___sancov_cntrs, __stop___sancov_cntrs byte //go:linkname __sanitizer_cov_pcs_init __sanitizer_cov_pcs_init //go:cgo_import_static __sanitizer_cov_pcs_init