linux-kernel - Re: [patch] PCI: check the return value of device_create_bin_file() in pci_create

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Message-ID: <alpine.LNX.1.10.0808051224350.5671@titan.stealer.net>
Date:	Tue, 5 Aug 2008 12:39:31 +0200 (CEST)
From:	Sven Wegener <sven.wegener@...aler.net>
To:	Simon Horman <horms@...ge.net.au>
cc:	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	Jesse Barnes <jbarnes@...tuousgeek.org>
Subject: Re: [patch] PCI: check the return value of device_create_bin_file()
 in	pci_create_bus()

On Tue, 5 Aug 2008, Simon Horman wrote:

> Check the return value of device_create_bin_file in pci_create_bus,
> unwind if neccessary, and propogate any errors to the caller.
> 
> Signed-off-by: Simon Horman <horms@...ge.net.au>
> 
> --- 
> 
> drivers/pci/probe.c: In function `pci_create_bus':
> drivers/pci/probe.c:66: warning: ignoring return value of `device_create_bin_file', declared with attribute warn_unused_result
> drivers/pci/probe.c:74: warning: ignoring return value of `device_create_bin_file', declared with attribute warn_unused_result
> 
> # ia64-unknown-linux-gnu-gcc --version
> ia64-unknown-linux-gnu-gcc (GCC) 3.4.5
> Copyright (C) 2004 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions.  There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> 
> Index: linux-2.6/drivers/pci/probe.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/probe.c	2008-08-05 19:58:43.000000000 +1000
> +++ linux-2.6/drivers/pci/probe.c	2008-08-05 19:59:15.000000000 +1000
> @@ -53,26 +53,37 @@ EXPORT_SYMBOL(no_pci_devices);
>   * a per-bus basis.  This routine creates the files and ties them into
>   * their associated read, write and mmap files from pci-sysfs.c
>   */
> -static void pci_create_legacy_files(struct pci_bus *b)
> +static int pci_create_legacy_files(struct pci_bus *b)
>  {
> +	int error;
> +
>  	b->legacy_io = kzalloc(sizeof(struct bin_attribute) * 2,
>  			       GFP_ATOMIC);
> -	if (b->legacy_io) {
> -		b->legacy_io->attr.name = "legacy_io";
> -		b->legacy_io->size = 0xffff;
> -		b->legacy_io->attr.mode = S_IRUSR | S_IWUSR;
> -		b->legacy_io->read = pci_read_legacy_io;
> -		b->legacy_io->write = pci_write_legacy_io;
> -		device_create_bin_file(&b->dev, b->legacy_io);
> -
> -		/* Allocated above after the legacy_io struct */
> -		b->legacy_mem = b->legacy_io + 1;
> -		b->legacy_mem->attr.name = "legacy_mem";
> -		b->legacy_mem->size = 1024*1024;
> -		b->legacy_mem->attr.mode = S_IRUSR | S_IWUSR;
> -		b->legacy_mem->mmap = pci_mmap_legacy_mem;
> -		device_create_bin_file(&b->dev, b->legacy_mem);
> +	if (!b->legacy_io)
> +		return -ENOMEM;
> +
> +	b->legacy_io->attr.name = "legacy_io";
> +	b->legacy_io->size = 0xffff;
> +	b->legacy_io->attr.mode = S_IRUSR | S_IWUSR;
> +	b->legacy_io->read = pci_read_legacy_io;
> +	b->legacy_io->write = pci_write_legacy_io;
> +	error = device_create_bin_file(&b->dev, b->legacy_io);
> +	if (error)
> +		return error;

I'd release the memory here and NULLify legacy_io.

> +
> +	/* Allocated above after the legacy_io struct */
> +	b->legacy_mem = b->legacy_io + 1;
> +	b->legacy_mem->attr.name = "legacy_mem";
> +	b->legacy_mem->size = 1024*1024;
> +	b->legacy_mem->attr.mode = S_IRUSR | S_IWUSR;
> +	b->legacy_mem->mmap = pci_mmap_legacy_mem;
> +	error = device_create_bin_file(&b->dev, b->legacy_mem);
> +	if (error) {
> +		device_remove_bin_file(&b->dev, b->legacy_io);
> +		return error;

Here too.

Reason: If we fail to create the legacy_io file, legacy_mem will still be 
NULL, because it has been not initialized at that point. But we will try 
to remove it in pci_remove_legacy_files and in sysfs_remove_bin_file 
we're going to derefence it and blow up.

>  	}
> +
> +	return 0;
>  }
>
>  void pci_remove_legacy_files(struct pci_bus *b)
> @@ -84,7 +95,7 @@ void pci_remove_legacy_files(struct pci_
>  	}
>  }
>  #else /* !HAVE_PCI_LEGACY */
> -static inline void pci_create_legacy_files(struct pci_bus *bus) { return; }
> +static inline int pci_create_legacy_files(struct pci_bus *bus) { return 0; }
>  void pci_remove_legacy_files(struct pci_bus *bus) { return; }
>  #endif /* HAVE_PCI_LEGACY */
>  
> @@ -1157,7 +1168,9 @@ struct pci_bus * pci_create_bus(struct d
>  		goto dev_create_file_err;
>  
>  	/* Create legacy_io and legacy_mem files for this bus */
> -	pci_create_legacy_files(b);
> +	error = pci_create_legacy_files(b);
> +	if (error)
> +		goto pci_create_legacy_files_err;
>  
>  	b->number = b->secondary = bus;
>  	b->resource[0] = &ioport_resource;
> @@ -1167,6 +1180,8 @@ struct pci_bus * pci_create_bus(struct d
>  
>  	return b;
>  
> +pci_create_legacy_files_err:
> +	device_remove_file(&b->dev, &dev_attr_cpuaffinity);
>  dev_create_file_err:
>  	device_unregister(&b->dev);
>  class_dev_reg_err:
--
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