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Re: [PATCH] xen: fix memory leak on error in vcpu_create


  • To: Stewart Hildebrand <stewart.hildebrand@xxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>
  • From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
  • Date: Tue, 29 Jul 2025 22:11:44 +0100
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  • Cc: Anthony PERARD <anthony.perard@xxxxxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Julien Grall <julien@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
  • Delivery-date: Tue, 29 Jul 2025 21:11:49 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 29/07/2025 10:08 pm, Stewart Hildebrand wrote:
> On 7/29/25 04:32, Jan Beulich wrote:
>> On 28.07.2025 22:09, Andrew Cooper wrote:
>>> On 28/07/2025 8:52 pm, Stewart Hildebrand wrote:
>>>> In vcpu_create after scheduler data is allocated, if
>>>> vmtrace_alloc_buffer fails, it will jump to the wrong cleanup label
>>>> resulting in a memory leak. Correct the label.
>>>>
>>>> Fixes: 217dd79ee292 ("xen/domain: Add vmtrace_size domain creation 
>>>> parameter")
>>>> Signed-off-by: Stewart Hildebrand <stewart.hildebrand@xxxxxxx>
>>> Urgh, sorry for breaking this.  Ultimately it comes from having two
>>> different error handling schemes.
>>>
>>> This patch is probably ok to start with (and to backport), but a better
>>> fix would be to handle sched and wq in vcpu_teardown().  That way we get
>>> a single failure path that does the correct thing irrespective.
>> I agree, and that variant would apparently be as easily backportable.
>> Stewart, are you up for going that route?
> Yep, I'll give it a try

Just as a heads up before you start, the key is to ensure that anything
called in *_teardown() is idempotent.

~Andrew



 


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