Re: [Libvir] Segfault with invalid virConnectPtr
On Fri, Aug 24, 2007 at 10:41:55AM +0100, Richard W.M. Jones wrote:
Program terminated with signal 11, Segmentation fault.
#0 0x0000003d8b472a1b in free () from /lib64/libc.so.6
(gdb) bt
#0 0x0000003d8b472a1b in free () from /lib64/libc.so.6
#1 0x00002aaaaaae8dd7 in virResetError (err=0x33535c8) at virterror.c:111
#2 0x00002aaaaaae8fce in __virRaiseError (conn=0x33535a0, dom=0x0,
net=0x0,
domain=0, code=6, level=VIR_ERR_ERROR,
str1=0x2aaaaab0c678 "invalid connection pointer in %s",
str2=0x2aaaaab08560 "virConnectNumOfDomains", str3=0x0, int1=0,
int2=0,
msg=0x2aaaaab0c678 "invalid connection pointer in %s") at
virterror.c:358
#3 0x00002aaaaaacfa8e in virLibConnError (conn=0x33535a0,
error=VIR_ERR_INVALID_CONN, info=0x2aaaaab08560
"virConnectNumOfDomains")
at libvirt.c:127
#4 0x00002aaaaaad1052 in virConnectNumOfDomains (conn=0x736e6961)
at libvirt.c:758
#5 0x000000000043fa4e in ?? ()
A preliminary look at the code seems to indicate a fault in this logic:
int
virConnectNumOfDomains(virConnectPtr conn)
{
DEBUG("conn=%p", conn);
if (!VIR_IS_CONNECT(conn)) {
virLibConnError(conn, VIR_ERR_INVALID_CONN, __FUNCTION__);
The VIR_IS_CONNECT macro is defined as:
#define VIR_CONNECT_MAGIC 0x4F23DEAD
#define VIR_IS_CONNECT(obj) ((obj) && (obj)->magic==VIR_CONNECT_MAGIC)
Obviously if VIR_IS_CONNECT fails then "conn" should not be used
further, so calling virLibConnError (conn, ...) is wrong.
yes that need to be fixed by passing NULL.
Personally I
think when we detect memory corruption in a C program we should just
call abort().
in a program you can call exit(), doing so in a library is an heresy,
so definitely no. It may not be a memory corruption, just a programming
error, a NULL pointer or something. Bringing down the user program from
a library is the best way to piss of your user base.
I'll see if I can come up with a patch to fix this later ... at
the
the fix at the libvirt level is just to pass NULL there.
Daniel
--
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Daniel Veillard | virtualization library http://libvirt.org/
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