At 04/19/2012 04:40 PM, Alex Jia Wrote:
> On 04/19/2012 04:19 PM, Wen Congyang wrote:
>> At 04/19/2012 04:09 PM, Alex Jia Wrote:
>>> Detected by valgrind.
>>>
>>> * tools/virsh.c (cmdBlockPull): fix uninitialized memory usage.
>>>
>>> * How to reproduce?
>>> $ qemu-img create /var/lib/libvirt/images/test 1M
>>> $ cat> /tmp/test.xml<<EOF
>>> <domain type='qemu'>
>>> <name>test</name>
>>> <memory>219200</memory>
>>> <vcpu>1</vcpu>
>>> <os>
>>> <type arch='x86_64'>hvm</type>
>>> <boot dev='hd'/>
>>> </os>
>>> <devices>
>>> <disk type='file' device='disk'>
>>> <driver name='qemu' type='raw'/>
>>> <source file='/var/lib/libvirt/images/test'/>
>>> <target dev='vda' bus='virtio'/>
>>> </disk>
>>> <input type='mouse' bus='ps2'/>
>>> <graphics type='spice' autoport='yes' listen='0.0.0.0'/>
>>> </devices>
>>> </domain>
>>> EOF
>>> $ virsh define /tmp/test.xml
>>> $ valgrind -v virsh blockpull test /var/lib/libvirt/images/test --wait
>>>
>>> actual result:
>>>
>>> ==10906== 1 errors in context 1 of 1:
>>> ==10906== Syscall param rt_sigaction(act->sa_flags) points to
>>> uninitialised byte(s)
>>> ==10906== at 0x39CF80F5BE: __libc_sigaction (sigaction.c:67)
>>> ==10906== by 0x43016C: cmdBlockPull (virsh.c:7638)
>>> ==10906== by 0x4150D4: vshCommandRun (virsh.c:18574)
>>> ==10906== by 0x425E73: main (virsh.c:20178)
>>> ==10906== Address 0x7fefffae8 is on thread 1's stack
>>>
>>>
>>> Signed-off-by: Alex Jia<ajia@xxxxxxxxxx>
>>> ---
>>> tools/virsh.c | 1 +
>>> 1 files changed, 1 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/tools/virsh.c b/tools/virsh.c
>>> index 95ed7bc..4e4ca57 100644
>>> --- a/tools/virsh.c
>>> +++ b/tools/virsh.c
>>> @@ -7634,6 +7634,7 @@ cmdBlockPull(vshControl *ctl, const vshCmd *cmd)
>>>
>>> intCaught = 0;
>>> sig_action.sa_sigaction = vshCatchInt;
>>> + sigemptyset((sigset_t *)&sig_action.sa_flags);
>> Why using sigemptyset here? You should use 'sig_action.sa_flags = 0'.
> Yeah, I think 'sig_action.sa_flags = 0' is right, but I don't know what
> the difference are,
> could you explain more?
sigset_t is:
# define _SIGSET_NWORDS (1024 / (8 * sizeof (unsigned long int)))
typedef struct
{
unsigned long int __val[_SIGSET_NWORDS];
} __sigset_t;
The length of sigset is larger than sizeof(int)
If you use sigemptyset() to clear flags, it will affect the memory after flags.
It is very dangerous!!!
Thanks
Wen Congyang
>
> Thanks,
> Alex
>> Thanks
>> Wen Congyang
>>
>>> sigemptyset(&sig_action.sa_mask);
>>> sigaction(SIGINT,&sig_action,&old_sig_action);
>>>
>
>
--
libvir-list mailing list
libvir-list@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/libvir-list