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[88.21.202.17]) by smtp.gmail.com with ESMTPSA id z12sm10314018wrq.7.2020.05.18.03.25.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 May 2020 03:25:53 -0700 (PDT) From: =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= To: qemu-devel@nongnu.org Subject: [RFC PATCH] hw/i386/vmport: Allow QTest use without crashing Date: Mon, 18 May 2020 12:25:51 +0200 Message-Id: <20200518102551.8516-1-f4bug@amsat.org> X-Mailer: git-send-email 2.21.3 MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::441; envelope-from=philippe.mathieu.daude@gmail.com; helo=mail-wr1-x441.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FORGED_FROMDOMAIN=0.001, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.249, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eduardo Habkost , "Michael S. Tsirkin" , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= , Alexander Bulekov , Paolo Bonzini , =?utf-8?q?Philippe_Mathieu-Daud?= =?utf-8?b?w6k=?= , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Philippe Mathieu-Daudé Trying libFuzzer on the vmport device, we get: AddressSanitizer:DEADLYSIGNAL ================================================================= ==29476==ERROR: AddressSanitizer: SEGV on unknown address 0x000000008840 (pc 0x56448bec4d79 bp 0x7ffeec9741b0 sp 0x7ffeec9740e0 T0) ==29476==The signal is caused by a READ memory access. #0 0x56448bec4d78 in vmport_ioport_read (qemu-fuzz-i386+0x1260d78) #1 0x56448bb5f175 in memory_region_read_accessor (qemu-fuzz-i386+0xefb175) #2 0x56448bb30c13 in access_with_adjusted_size (qemu-fuzz-i386+0xeccc13) #3 0x56448bb2ea27 in memory_region_dispatch_read1 (qemu-fuzz-i386+0xecaa27) #4 0x56448bb2e443 in memory_region_dispatch_read (qemu-fuzz-i386+0xeca443) #5 0x56448b961ab1 in flatview_read_continue (qemu-fuzz-i386+0xcfdab1) #6 0x56448b96336d in flatview_read (qemu-fuzz-i386+0xcff36d) #7 0x56448b962ec4 in address_space_read_full (qemu-fuzz-i386+0xcfeec4) This is easily reproducible using: $ echo inb 0x5658 | qemu-system-i386 -M isapc,accel=qtest -qtest stdio [I 1589796572.009763] OPENED [R +0.008069] inb 0x5658 Segmentation fault (core dumped) $ coredumpctl gdb -q Program terminated with signal SIGSEGV, Segmentation fault. #0 0x00005605b54d0f21 in vmport_ioport_read (opaque=0x5605b7531ce0, addr=0, size=4) at hw/i386/vmport.c:77 77 eax = env->regs[R_EAX]; (gdb) p cpu $1 = (X86CPU *) 0x0 (gdb) bt #0 0x00005605b54d0f21 in vmport_ioport_read (opaque=0x5605b7531ce0, addr=0, size=4) at hw/i386/vmport.c:77 #1 0x00005605b53db114 in memory_region_read_accessor (mr=0x5605b7531d80, addr=0, value=0x7ffc9d261a30, size=4, shift=0, mask=4294967295, attrs=...) at memory.c:434 #2 0x00005605b53db5d4 in access_with_adjusted_size (addr=0, value=0x7ffc9d261a30, size=1, access_size_min=4, access_size_max=4, access_fn= 0x5605b53db0d2 , mr=0x5605b7531d80, attrs=...) at memory.c:544 #3 0x00005605b53de156 in memory_region_dispatch_read1 (mr=0x5605b7531d80, addr=0, pval=0x7ffc9d261a30, size=1, attrs=...) at memory.c:1396 #4 0x00005605b53de228 in memory_region_dispatch_read (mr=0x5605b7531d80, addr=0, pval=0x7ffc9d261a30, op=MO_8, attrs=...) at memory.c:1424 #5 0x00005605b537c80a in flatview_read_continue (fv=0x5605b7650290, addr=22104, attrs=..., ptr=0x7ffc9d261b4b, len=1, addr1=0, l=1, mr=0x5605b7531d80) at exec.c:3200 #6 0x00005605b537c95d in flatview_read (fv=0x5605b7650290, addr=22104, attrs=..., buf=0x7ffc9d261b4b, len=1) at exec.c:3239 #7 0x00005605b537c9e6 in address_space_read_full (as=0x5605b5f74ac0 , addr=22104, attrs=..., buf=0x7ffc9d261b4b, len=1) at exec.c:3252 #8 0x00005605b53d5a5d in address_space_read (len=1, buf=0x7ffc9d261b4b, attrs=..., addr=22104, as=0x5605b5f74ac0 ) at include/exec/memory.h:2401 #9 0x00005605b53d5a5d in cpu_inb (addr=22104) at ioport.c:88 X86CPU is NULL because QTest accelerator does not use CPU. Fix by returning default values when QTest accelerator is used. Reported-by: Clang AddressSanitizer Signed-off-by: Philippe Mathieu-Daudé --- hw/i386/vmport.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/hw/i386/vmport.c b/hw/i386/vmport.c index 1aaaab691a..4ec95f8778 100644 --- a/hw/i386/vmport.c +++ b/hw/i386/vmport.c @@ -24,6 +24,7 @@ #include "qemu/osdep.h" #include "hw/isa/isa.h" #include "sysemu/hw_accel.h" +#include "sysemu/qtest.h" #include "qemu/log.h" #include "vmport.h" #include "cpu.h" @@ -64,10 +65,14 @@ static uint64_t vmport_ioport_read(void *opaque, hwaddr addr, VMPortState *s = opaque; CPUState *cs = current_cpu; X86CPU *cpu = X86_CPU(cs); - CPUX86State *env = &cpu->env; + CPUX86State *env; unsigned char command; uint32_t eax; + if (qtest_enabled()) { + return -1; + } + env = &cpu->env; cpu_synchronize_state(cs); eax = env->regs[R_EAX]; @@ -90,6 +95,9 @@ static void vmport_ioport_write(void *opaque, hwaddr addr, { X86CPU *cpu = X86_CPU(current_cpu); + if (qtest_enabled()) { + return; + } cpu->env.regs[R_EAX] = vmport_ioport_read(opaque, addr, 4); } @@ -97,6 +105,9 @@ static uint32_t vmport_cmd_get_version(void *opaque, uint32_t addr) { X86CPU *cpu = X86_CPU(current_cpu); + if (qtest_enabled()) { + return -1; + } cpu->env.regs[R_EBX] = VMPORT_MAGIC; return 6; } @@ -105,6 +116,9 @@ static uint32_t vmport_cmd_ram_size(void *opaque, uint32_t addr) { X86CPU *cpu = X86_CPU(current_cpu); + if (qtest_enabled()) { + return -1; + } cpu->env.regs[R_EBX] = 0x1177; return ram_size; }