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Description of problem: If I configure a guest with serial console only and then attempt to take a screenshot, qemu crashes. Version-Release number of selected component (if applicable): qemu-kvm-0.12.1.2-2.172.el6.x86_64 How reproducible: 100% Steps to Reproduce: 1. configure qemu without a graphics device 2. send monitor command: screendump /path/to/file Actual results: qemu crashes Expected results: qemu returns an error Additional info: I have only reproduced this problem under libvirt, so I don't have a simple qemu command line reproducer. If it's not trivially reproducible for you, let me know and I'll get you access to a system exhibiting the behavior.
Reproducer: /usr/libexec/qemu-kvm -nographic -vga none Type 'Ctrl-A c' to get the monitor prompt, then try screendump. Upstream at least doesn't crash. Doesn't report an error though. Will look into this.
Reproduced this issue with steps and environment as follows: # uname -r;rpm -q qemu-kvm 2.6.32-220.el6.x86_64 qemu-kvm-0.12.1.2-2.209.el6.x86_64 1. configure qemu without a graphics device, say: /usr/libexec/qemu-kvm -nographic -vga none -nographic -vga none 2. Type 'Ctrl-A c' to get the monitor and issue screendump /path/to/file Actual Result: (qemu) screendump /home/screen-file Program received signal SIGSEGV, Segmentation fault. vga_hw_screen_dump (filename=0xf4a9e0 "/home/screen-file") at console.c:181 181 if (consoles[0]->hw_screen_dump) (gdb) bt #0 vga_hw_screen_dump (filename=0xf4a9e0 "/home/screen-file") at console.c:181 #1 0x0000000000412289 in do_screen_dump (mon=<value optimized out>, qdict=<value optimized out>, ret_data=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/monitor.c:1309 #2 0x0000000000412920 in monitor_call_handler (mon=<value optimized out>, cmd=0x591c58, params=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/monitor.c:4105 #3 0x00000000004176f0 in handle_user_command (mon=0xf07870, cmdline=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/monitor.c:4142 #4 0x000000000041781a in monitor_command_cb (mon=0xf07870, cmdline=<value optimized out>, opaque=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/monitor.c:4697 #5 0x00000000004aba2b in readline_handle_byte (rs=0xf07ce0, ch=<value optimized out>) at readline.c:369 #6 0x0000000000417a3c in monitor_read (opaque=<value optimized out>, buf=0x7fffffffcf1f "\r", size=1) at /usr/src/debug/qemu-kvm-0.12.1.2/monitor.c:4683 #7 0x00000000004bf79b in mux_chr_read (opaque=0xf07600, buf=0x7fffffffcf1f "\r", size=1) at qemu-char.c:442 #8 0x00000000004be1ff in qemu_chr_read (opaque=0xf07450) at qemu-char.c:170 #9 stdio_read (opaque=0xf07450) at qemu-char.c:794 #10 0x000000000040c43f in main_loop_wait (timeout=1000) at /usr/src/debug/qemu-kvm-0.12.1.2/vl.c:4024 #11 0x000000000042aefa in kvm_main_loop () at /usr/src/debug/qemu-kvm-0.12.1.2/qemu-kvm.c:2225 #12 0x000000000040de85 in main_loop (argc=<value optimized out>, argv=<value optimized out>, envp=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/vl.c:4234 #13 main (argc=<value optimized out>, argv=<value optimized out>, envp=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/vl.c:6470 Marking qa_ack+ according to above info.
Reproduced this issue with steps and environment as follows: # uname -r;rpm -q qemu-kvm 2.6.32-220.el6.x86_64 qemu-kvm-0.12.1.2-2.207.el6.x86_64 1. configure qemu without a graphics device: /usr/libexec/qemu-kvm -nographic -vga none 2. Type 'Ctrl-A c' to get the monitor and issue screendump /path/to/file Actual Result: (qemu) screendump /tmp/screen-file1 Program received signal SIGSEGV, Segmentation fault. vga_hw_screen_dump (filename=0xea69e0 "/tmp/screen-file1") at console.c:181 181 if (consoles[0]->hw_screen_dump) (gdb) bt #0 vga_hw_screen_dump (filename=0xea69e0 "/tmp/screen-file1") at console.c:181 #1 0x0000000000412239 in do_screen_dump (mon=<value optimized out>, qdict=<value optimized out>, ret_data=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/monitor.c:1309 #2 0x00000000004128d0 in monitor_call_handler (mon=<value optimized out>, cmd=0x591b18, params=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/monitor.c:4105 #3 0x00000000004176a0 in handle_user_command (mon=0xe5e570, cmdline=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/monitor.c:4142 #4 0x00000000004177ca in monitor_command_cb (mon=0xe5e570, cmdline=<value optimized out>, opaque=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/monitor.c:4697 #5 0x00000000004ab98b in readline_handle_byte (rs=0xe5e9e0, ch=<value optimized out>) at readline.c:369 #6 0x00000000004179ec in monitor_read (opaque=<value optimized out>, buf=0x7fffffffcb8f "\r", size=1) at /usr/src/debug/qemu-kvm-0.12.1.2/monitor.c:4683 #7 0x00000000004bf6fb in mux_chr_read (opaque=0xd6a650, buf=0x7fffffffcb8f "\r", size=1) at qemu-char.c:442 #8 0x00000000004be15f in qemu_chr_read (opaque=0xd5a490) at qemu-char.c:170 #9 stdio_read (opaque=0xd5a490) at qemu-char.c:794 #10 0x000000000040c3ef in main_loop_wait (timeout=1000) at /usr/src/debug/qemu-kvm-0.12.1.2/vl.c:4024 #11 0x000000000042aeaa in kvm_main_loop () at /usr/src/debug/qemu-kvm-0.12.1.2/qemu-kvm.c:2225 #12 0x000000000040de35 in main_loop (argc=<value optimized out>, argv=<value optimized out>, envp=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/vl.c:4234 #13 main (argc=<value optimized out>, argv=<value optimized out>, envp=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/vl.c:6470 Verified this issue with steps and environment as follows: # uname -r;rpm -q qemu-kvm 2.6.32-220.el6.x86_64 qemu-kvm-0.12.1.2-2.213.el6.x86_64 1. configure qemu without a graphics device: /usr/libexec/qemu-kvm -nographic -vga none 2. Type 'Ctrl-A c' to get the monitor and issue screendump /path/to/file Actual Result: (qemu) screendump /tmp/screen-file2 (qemu) info status VM status: running 3.check the result in host # ls /tmp/screen-file2 ls: cannot access /tmp/screen-file2: No such file or directory qemu neither crash nor report an error.According to Comment 2 ,this bug had been fixed.
Technical note added. If any revisions are required, please edit the "Technical Notes" field accordingly. All revisions will be proofread by the Engineering Content Services team. New Contents: Cause: Run qemu-kvm without graphics by passing -nographic argument and then try to do screendump. Consequence: Guest is destroyed as qemu-kvm crashes with segmentation fault. Fix: Check for valid screendump function pointer has been implemented prior to calling it. Result: qemu-kvm doesn't crash and continues running
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. http://rhn.redhat.com/errata/RHBA-2012-0746.html