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&gt; > > --- > > 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.