From 508b4ecc3935f0cffb6f8e302fb84941dae940c9 Mon Sep 17 00:00:00 2001 From: Ziyue Yang Date: Wed, 18 Jan 2017 16:02:41 +0800 Subject: gdbstub.c: fix GDB connection segfault caused by empty machines This patch is to fix the segmentation fault caused by attaching GDB to a QEMU instance initialized with "-M none" option. The bug can be reproduced by > ./qemu-system-x86_64 -M none -nographic -S -s and attach a GDB to it by > gdb -ex 'target remote :1234 The segmentation fault was originally caused by trying to read the information about CPU when communicating with GDB. However, it's impossible for any control flow to exist on an empty machine, nor can CPU's be hot plugged to an empty machine later by QOM commands. So I think simply disabling GDB connections on empty machines makes sense. Signed-off-by: Ziyue Yang Reviewed-by: Thomas Huth Signed-off-by: Michael Tokarev --- gdbstub.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'gdbstub.c') diff --git a/gdbstub.c b/gdbstub.c index de9b62b8f8..27e0923781 100644 --- a/gdbstub.c +++ b/gdbstub.c @@ -18,6 +18,7 @@ */ #include "qemu/osdep.h" #include "qapi/error.h" +#include "qemu/error-report.h" #include "qemu/cutils.h" #include "cpu.h" #ifdef CONFIG_USER_ONLY @@ -1732,6 +1733,12 @@ int gdbserver_start(const char *device) CharDriverState *mon_chr; ChardevCommon common = { 0 }; + if (!first_cpu) { + error_report("gdbstub: meaningless to attach gdb to a " + "machine without any CPU."); + return -1; + } + if (!device) return -1; if (strcmp(device, "none") != 0) { -- cgit 1.4.1 From 7ae6c571151cff785a225d6916269bbe199f0ab1 Mon Sep 17 00:00:00 2001 From: Ziyue Yang Date: Wed, 18 Jan 2017 16:03:29 +0800 Subject: gdbstub.c: update old error report statements Some updates from fprintf(stderr, ...) to error_report. Signed-off-by: Ziyue Yang Reviewed-by: Thomas Huth Signed-off-by: Michael Tokarev --- gdbstub.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'gdbstub.c') diff --git a/gdbstub.c b/gdbstub.c index 27e0923781..2d18ed73be 100644 --- a/gdbstub.c +++ b/gdbstub.c @@ -638,8 +638,8 @@ void gdb_register_coprocessor(CPUState *cpu, *p = s; if (g_pos) { if (g_pos != s->base_reg) { - fprintf(stderr, "Error: Bad gdb register numbering for '%s'\n" - "Expected %d got %d\n", xml, g_pos, s->base_reg); + error_report("Error: Bad gdb register numbering for '%s', " + "expected %d got %d", xml, g_pos, s->base_reg); } else { cpu->gdb_num_g_regs = cpu->gdb_num_regs; } @@ -891,7 +891,7 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf) } case 'k': /* Kill the target */ - fprintf(stderr, "\nQEMU: Terminated via GDBstub\n"); + error_report("QEMU: Terminated via GDBstub"); exit(0); case 'D': /* Detach packet */ @@ -1359,8 +1359,8 @@ void gdb_do_syscallv(gdb_syscall_complete_cb cb, const char *fmt, va_list va) break; default: bad_format: - fprintf(stderr, "gdbstub: Bad syscall format string '%s'\n", - fmt - 1); + error_report("gdbstub: Bad syscall format string '%s'", + fmt - 1); break; } } else { -- cgit 1.4.1