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From: Alexander Bulekov <alxndr@bu.edu>
To: qemu-devel@nongnu.org
Cc: Laurent Vivier <lvivier@redhat.com>,
	Thomas Huth <thuth@redhat.com>, Alexander Bulekov <alxndr@bu.edu>,
	darren.kenny@oracle.com, bsd@redhat.com, stefanha@redhat.com,
	Paolo Bonzini <pbonzini@redhat.com>
Subject: [PATCH 3/4] fuzz: add mangled object name to linker script
Date: Mon, 11 May 2020 23:01:32 -0400	[thread overview]
Message-ID: <20200512030133.29896-4-alxndr@bu.edu> (raw)
In-Reply-To: <20200512030133.29896-1-alxndr@bu.edu>

Previously, we relied on "FuzzerTracePC*(.bss*)" to place libfuzzer's
fuzzer::TPC object into our contiguous shared-memory region. This does
not work for some libfuzzer builds, so this addition identifies the
region by its mangled name: *(.bss._ZN6fuzzer3TPCE);

Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
---
 tests/qtest/fuzz/fork_fuzz.ld | 5 +++++
 1 file changed, 5 insertions(+)

This isn't ideal, but I looked at the libfuzzer builds packaged for
debian, for versions 6, 7, 8, 9, 10 and 11 and this (mangled) object
name appears consistently in the symbol tables.

diff --git a/tests/qtest/fuzz/fork_fuzz.ld b/tests/qtest/fuzz/fork_fuzz.ld
index e086bba873..bfb667ed06 100644
--- a/tests/qtest/fuzz/fork_fuzz.ld
+++ b/tests/qtest/fuzz/fork_fuzz.ld
@@ -28,6 +28,11 @@ SECTIONS
 
       /* Internal Libfuzzer TracePC object which contains the ValueProfileMap */
       FuzzerTracePC*(.bss*);
+      /*
+       * In case the above line fails, explicitly specify the (mangled) name of
+       * the object we care about
+       */
+       *(.bss._ZN6fuzzer3TPCE);
   }
   .data.fuzz_end : ALIGN(4K)
   {
-- 
2.26.2



  parent reply	other threads:[~2020-05-12  3:02 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-12  3:01 [PATCH 0/4] fuzz: misc changes for oss-fuzz compatability Alexander Bulekov
2020-05-12  3:01 ` [PATCH 1/4] fuzz: add datadir " Alexander Bulekov
2020-05-12  7:59   ` Darren Kenny
2020-05-20 16:51   ` Philippe Mathieu-Daudé
2020-05-20 18:07     ` Alexander Bulekov
2020-05-12  3:01 ` [PATCH 2/4] fuzz: fix typo in i440fx-qtest-reboot arguments Alexander Bulekov
2020-05-12  7:59   ` Darren Kenny
2020-05-12  8:14   ` Philippe Mathieu-Daudé
2020-05-12  3:01 ` Alexander Bulekov [this message]
2020-05-12  8:01   ` [PATCH 3/4] fuzz: add mangled object name to linker script Darren Kenny
2020-05-12  3:01 ` [PATCH 4/4] fuzz: run the main-loop in fork-server process Alexander Bulekov
2020-05-12  8:00   ` Darren Kenny
2020-05-19 15:47 ` [PATCH 0/4] fuzz: misc changes for oss-fuzz compatability Alexander Bulekov
2020-05-26 15:34 ` Stefan Hajnoczi

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