Re: [PATCH] powerpc/mpic: Fix memory leak of mpic on error paths

[Amit Machhiwal <amachhiw@linux.ibm.com>]

Hi Jyoti,

For some reason, you response to this thread is not appearing on the list.  I
think you mail client is messing up the "In-Reply-To" information in the
header.  Fix look into fixing it.

For now, I'll qoute your reply here with my further response.

On 2026/09/24 03:05 PM, Amit Machhiwal wrote:
> On 2026/09/24 12:00 PM, Jyoti Gupta wrote:
> > mpic_alloc() allocates struct mpic (and optionally the protected
> > sources bitmap) but does not free them when mpic_setup_error_int() or
> > irq_domain_create_linear() fails, leaking the memory.
> > 
> > Initialise mpic to NULL and free the bitmap and the mpic in the common
> > error path before dropping the device node reference. The register
> > mappings are not released here.
> > 
> > Signed-off-by: Jyoti Gupta <jyoti@linux.ibm.com>
> 
> I see a couple of problems with this patch:
> 
> 1. The patch does not apply.  Both "git apply" and "git am" fail on this patch.
>    I think the context lines around the irq_domain_create_linear() call have
>    tabs converted to spaces, which causes the context match to fail.
> 
>       ❯ git apply ./20260924_jyoti_powerpc_mpic_fix_memory_leak_of_mpic_on_error_paths.mbx --check --verbose
>       Checking patch arch/powerpc/sysdev/mpic.c...
>       error: while searching for:
>       						 intvec_top,
>       						 &mpic_host_ops, mpic);
> 
>       	/*
>       	 * FIXME: The code leaks the MPIC object and mappings here; this
>       	 * is very unlikely to fail but it ought to be fixed anyways.
>       	 */
>       	if (mpic->irqhost == NULL)
>       		goto err_of_node_put;
> 
> 
>       error: patch failed: arch/powerpc/sysdev/mpic.c:1488
>       error: arch/powerpc/sysdev/mpic.c: patch does not apply
> 
>    Please regenerate with:
> 
>      git format-patch -1
> 
>    and verify with:
> 
>      git apply --check <patch>
> 
>    before resending.
> 
> 2. The mpic_setup_error_int() leak is not actually fixed.  The commit message
>    says both mpic_setup_error_int() and irq_domain_create_linear() failure paths
>    are fixed, but the former still does a bare return NULL:
> 
>      if (fsl_version >= 0x401) {
>          ret = mpic_setup_error_int(mpic, intvec_top - 13);
>          if (ret)
>              return NULL;   /* <-- still leaks mpic and mpic->protected */
>      }
> 
>    This needs to become:
> 
>          if (ret)
>              goto err_of_node_put;
> 
> Thanks,
> Amit
> 
> > ---
> >  arch/powerpc/sysdev/mpic.c | 9 ++++-----
> >  1 file changed, 4 insertions(+), 5 deletions(-)
> > 
> > diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
> > index 6e8fa94985f3..e777b33f170d 100644
> > --- a/arch/powerpc/sysdev/mpic.c
> > +++ b/arch/powerpc/sysdev/mpic.c
> > @@ -1221,7 +1221,7 @@ struct mpic * __init mpic_alloc(struct device_node *node,
> >  				const char *name)
> >  {
> >  	int i, psize, intvec_top;
> > -	struct mpic *mpic;
> > +	struct mpic *mpic = NULL;
> >  	u32 greg_feature;
> >  	const char *vers;
> >  	const u32 *psrc;
> > @@ -1488,10 +1488,6 @@ struct mpic * __init mpic_alloc(struct device_node *node,
> >  						 intvec_top,
> >  						 &mpic_host_ops, mpic);
> >  
> > -	/*
> > -	 * FIXME: The code leaks the MPIC object and mappings here; this
> > -	 * is very unlikely to fail but it ought to be fixed anyways.
> > -	 */
> >  	if (mpic->irqhost == NULL)
> >  		goto err_of_node_put;
> >  
> > @@ -1527,6 +1523,9 @@ struct mpic * __init mpic_alloc(struct device_node *node,
> >  	return mpic;
> >  
> >  err_of_node_put:
> > +	if (mpic)
> > +		bitmap_free(mpic->protected);
> > +	kfree(mpic);
> >  	of_node_put(node);
> >  	return NULL;
> >  }
> > -- 
> > 2.55.0
> > 
> > 
> 

Response from Jyoti:

> The mpic_setup_error_int() leak is intentionally left to a separate patch
> already under

If that's the case, you shouldn't have mentioned about this change in the commit
log of this patch.  The commit log needs to be updated accordingly if that's
what your intent is.

>  review:
> "[PATCH] powerpc: Fix missing of_node_put() calls"
> That patch converts the return NULL at line 1392 to goto err_of_node_put as
> part of a

I could only find below:

https://lore.kernel.org/all/5cef10ab1610113fe162cec1dffd97f3@linux.ibm.com/

Sorry, but I don't think thats the right way to send a patch.  You seem to have
replied to the email which did not land into the mailing lists at all.  Having
said that, I think fixing this particular path in mpic_alloc() would make more
sense in the current patch itself.

Please look into fixing your mail client and send the patches/responses in
proper format.

Thanks,
Amit.

> broader of_node_put() fix series. This patch focuses only on the
> irq_domain_create_linear()
> failure path.
> 
> Thanks,
> Jyoti