Re: [libvirt] [PATCH] util: Prevent libvirtd crash from virPCIDeviceAddressIsEqual()
On 04/29/2013 02:48 AM, Laine Stump wrote:
On 04/28/2013 06:12 AM, Alex Jia wrote:
> GDB backtrace:
>
> Breakpoint 1, virPCIGetVirtualFunctionIndex (pf_sysfs_device_link=0x7fc04400f470
"/sys/bus/pci/devices/0000:03:00.1", vf_sysfs_device_link=<optimized out>,
vf_index=vf_index@entry=0x7fc06897b8f4)
> at util/virpci.c:2107
> 2107 if (virPCIDeviceAddressIsEqual(vf_bdf, virt_fns[i])) {
> (gdb) p *vf_bdf
> $1 = {domain = 0, bus = 3, slot = 16, function = 1}
> (gdb) l
> 2102 "virtual_functions"),
pf_sysfs_device_link);
> 2103 goto out;
> 2104 }
> 2105
> 2106 for (i = 0; i< num_virt_fns; i++) {
> 2107 if (virPCIDeviceAddressIsEqual(vf_bdf, virt_fns[i])) {
> 2108 *vf_index = i;
> 2109 ret = 0;
> 2110 break;
> 2111 }
> (gdb) p num_virt_fns
> $46 = 2
> (gdb) p virt_fns[0]
> $48 = (virPCIDeviceAddressPtr) 0x0
> (gdb) s
> virPCIDeviceAddressIsEqual (bdf2=0x0, bdf1=0x7fc04400f330) at util/virpci.c:1844
> 1844 (bdf1->slot == bdf2->slot)&&
> (gdb) s
>
> Program received signal SIGSEGV, Segmentation fault.
>
> RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=957416
>
> Signed-off-by: Alex Jia<ajia(a)redhat.com>
> ---
> src/util/virpci.c | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/src/util/virpci.c b/src/util/virpci.c
> index 97bba74..dda044c 100644
> --- a/src/util/virpci.c
> +++ b/src/util/virpci.c
> @@ -1897,7 +1897,8 @@ static bool
> virPCIDeviceAddressIsEqual(virPCIDeviceAddressPtr bdf1,
> virPCIDeviceAddressPtr bdf2)
> {
> - return ((bdf1->domain == bdf2->domain)&&
> + return (bdf1&& bdf2&&
> + (bdf1->domain == bdf2->domain)&&
> (bdf1->bus == bdf2->bus)&&
> (bdf1->slot == bdf2->slot)&&
> (bdf1->function == bdf2->function));
NACK.
This patch only fixes the symptom (not the root cause), and only in the
case of starting a domain with an<interface type='hostdev'. It doesn't
fix the second crash described in the BZ when running virsh
nodedev-dumpxml - the code path of that doesn't ever get to
Yes, I just noticed this, it should be different code path.
virPCIDeviceAddressIsEqual() (but *does* call the function that
actually
has the bug).
Yes, another bug.
The root cause of these crashes was a typo introduced just before
the
release of 1.0.4. I found that problem and pushed the correct patch on
April 9:
http://libvirt.org/git/?p=libvirt.git;a=commit;h=9579b6bc209b46a0f079b214...
It should be okay if the patch is backported into rhel.
(Beyond that, I don't like the idea of ignoring a NULL pointer -
virPCIDeviceAddressIsEqual should always be passed non-NULL pointers,
and its only current caller does guarantee that (except for when it has
a bug). If we want virPCIDeviceAddressIsEqual to do something with NULL
pointers, it should be logging an error and failing, but that would
complicate the interface to the function beyond just returning a
true/false (it would have to be tri-state, and the caller would need to
Yes, the function interface will be more complex and return value should
be tri-state not simple true/false.
check all three possibilities). I think in this case it's better
for the
caller to make sure the pointers it sends are valid.)
Yes, a simple way is the caller makes sure pointers is Non-NULL, maybe,
we need also to add comment "The caller should make sure the pointers
it sends are valid" into the virPCIDeviceAddressIsEqual(). However,
in order to avoid the caller missing argument judgement, I think we
should also fix virPCIDeviceAddressIsEqual().
Thanks for your comments,
Alex
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