Re: [libvirt] [PATCH] qemu: fix memory leak in qemuAgentGetFSInfo
On Tue, Mar 10, 2015 at 10:32:04AM +0100, Ján Tomko wrote:
On Tue, Mar 10, 2015 at 01:56:11PM +0800, Chen Fan wrote:
> in virDomainFSInfoFree(), don't free the virDomainFSInfo data.
>
> ==10670== 80 bytes in 2 blocks are definitely lost in loss record 576 of 793
> ==10670== at 0x4A06BC3: calloc (vg_replace_malloc.c:618)
> ==10670== by 0x509DEBD: virAlloc (viralloc.c:144)
> ==10670== by 0x19FBD558: qemuAgentGetFSInfo (qemu_agent.c:1837)
> ==10670== by 0x1A03CF91: qemuDomainGetFSInfo (qemu_driver.c:19238)
>
> Signed-off-by: Chen Fan <chen.fan.fnst(a)cn.fujitsu.com>
> ---
> src/libvirt-domain.c | 2 ++
> 1 file changed, 2 insertions(+)
This does fix the memory leak and makes the function behave like it's
documented in virDomainGetFSInfo and virDomainFSInfoFree:
http://libvirt.org/html/libvirt-libvirt-domain.html#virDomainGetFSInfo
http://libvirt.org/html/libvirt-libvirt-domain.html#virDomainFSInfoFree
But it changes the public API - if there are applications that already
work around this function by freeing the info, this change would
introduce a double free.
Well, this is a good point that we might break somebody's application, but the
virDomainFSInfoFree is the only one *Free API that doesn't call free/unref on
passed argument. In the documentation the @info is an array and we specifically
says that calling virDomainFSInfoFree on each element and then just free the
@info is sufficient, but it isn't and there will be a memory leak. It changes
behavior of public API to correctly free the allocated memory as documentation
says. Let's hear another opinion, but I'm for fixing it.
Pavel
I would NACK this if the documentation for both APIs didn't say that's
how this function should behave.
I'd like to hear a second opinion.
Jan
>
> diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
> index 04545fd..7f8a7ce 100644
> --- a/src/libvirt-domain.c
> +++ b/src/libvirt-domain.c
> @@ -11337,4 +11337,6 @@ virDomainFSInfoFree(virDomainFSInfoPtr info)
> for (i = 0; i < info->ndevAlias; i++)
> VIR_FREE(info->devAlias[i]);
> VIR_FREE(info->devAlias);
> +
> + VIR_FREE(info);
> }
> --
> 1.9.3
>
> --
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