[PATCH] ARM: Ignore memory tags with invalid data

[PATCH] ARM: Ignore memory tags with invalid data

[Corey Minyard]

From: Corey Minyard <minyard@acm.org>

The DNS-323 system has several bogus memory entries in the tag table,
and it caused the system to crash at startup.  Ignore tag entries that
are obviously bogus.

Signed-off-by: Corey Minyard <minyard@acm.org>
---
 arch/arm/kernel/setup.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index bf56eb3..dfdb469 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -630,7 +630,12 @@ __tagtable(ATAG_CORE, parse_tag_core);
 
 static int __init parse_tag_mem32(const struct tag *tag)
 {
-	if (meminfo.nr_banks >= NR_BANKS) {
+	/*
+	 * Make sure that the memory size is non-zero, page aligned,
+	 * and that it doesn't overflow the meminfo table.
+	 */
+	if (meminfo.nr_banks >= NR_BANKS || tag->u.mem.size & ~PAGE_MASK ||
+	    tag->u.mem.size == 0 || tag->u.mem.start & ~PAGE_MASK) {
 		printk(KERN_WARNING
 		       "Ignoring memory bank 0x%08x size %dKB\n",
 			tag->u.mem.start, tag->u.mem.size / 1024);

Re: [PATCH] ARM: Ignore memory tags with invalid data

[Ben Dooks]

On Mon, Jan 21, 2008 at 10:05:56PM -0600, Corey Minyard wrote:
> From: Corey Minyard <minyard@acm.org>
> 
> The DNS-323 system has several bogus memory entries in the tag table,
> and it caused the system to crash at startup.  Ignore tag entries that
> are obviously bogus.

This should have gone to the linux-arm-kernel mailing list as well,
so that all the people interested in ARM can see it as soon as
possible. See linux-arm-kernel@lists.arm.linux.org.uk

The only suggestion I could think of would to be change to having
an check_tag_mem32() function, or put each check on its own line
to make it easier to read what each check is doing.

ie:
	if (meminfo.nr_banks >= NR_BANKS ||
	    tag->u.mem.size & ~PAGE_MASK || /* size is unaligned */
	    tag->u.mem.size == 0 ||	    /* no memory here */
	    tag->u.mem.start & ~PAGE_MASK)  /* start is unaligned */ 
	{

(even without the comments it makes it easier to see what each test
is.
 
> Signed-off-by: Corey Minyard <minyard@acm.org>
> ---
>  arch/arm/kernel/setup.c |    7 ++++++-
>  1 files changed, 6 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> index bf56eb3..dfdb469 100644
> --- a/arch/arm/kernel/setup.c
> +++ b/arch/arm/kernel/setup.c
> @@ -630,7 +630,12 @@ __tagtable(ATAG_CORE, parse_tag_core);
>  
>  static int __init parse_tag_mem32(const struct tag *tag)
>  {
> -	if (meminfo.nr_banks >= NR_BANKS) {
> +	/*
> +	 * Make sure that the memory size is non-zero, page aligned,
> +	 * and that it doesn't overflow the meminfo table.
> +	 */
> +	if (meminfo.nr_banks >= NR_BANKS || tag->u.mem.size & ~PAGE_MASK ||
> +	    tag->u.mem.size == 0 || tag->u.mem.start & ~PAGE_MASK) {
>  		printk(KERN_WARNING
>  		       "Ignoring memory bank 0x%08x size %dKB\n",
>  			tag->u.mem.start, tag->u.mem.size / 1024);
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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-- 
Ben (ben@fluff.org, http://www.fluff.org/)

  'a smiley only costs 4 bytes'

Re: [PATCH] ARM: Ignore memory tags with invalid data

[Corey Minyard]

Ben Dooks wrote:
> On Mon, Jan 21, 2008 at 10:05:56PM -0600, Corey Minyard wrote:
>   
>> From: Corey Minyard <minyard@acm.org>
>>
>> The DNS-323 system has several bogus memory entries in the tag table,
>> and it caused the system to crash at startup.  Ignore tag entries that
>> are obviously bogus.
>>     
>
> This should have gone to the linux-arm-kernel mailing list as well,
> so that all the people interested in ARM can see it as soon as
> possible. See linux-arm-kernel@lists.arm.linux.org.uk
>   
You have to be a member to post, and I'm not a member.  I guess I'll 
join, though it seems somewhat pointless for a single patch.

> The only suggestion I could think of would to be change to having
> an check_tag_mem32() function, or put each check on its own line
> to make it easier to read what each check is doing.
>
> ie:
> 	if (meminfo.nr_banks >= NR_BANKS ||
> 	    tag->u.mem.size & ~PAGE_MASK || /* size is unaligned */
> 	    tag->u.mem.size == 0 ||	    /* no memory here */
> 	    tag->u.mem.start & ~PAGE_MASK)  /* start is unaligned */ 
> 	{
>
> (even without the comments it makes it easier to see what each test
> is.
>   
That's fine, it is easier to read.

Thanks,

-corey

Re: [PATCH] ARM: Ignore memory tags with invalid data

[Russell King]

On Tue, Jan 22, 2008 at 08:34:10AM -0600, Corey Minyard wrote:
> Ben Dooks wrote:
> >This should have gone to the linux-arm-kernel mailing list as well,
> >so that all the people interested in ARM can see it as soon as
> >possible. See linux-arm-kernel@lists.arm.linux.org.uk
>
> You have to be a member to post, and I'm not a member.  I guess I'll 
> join, though it seems somewhat pointless for a single patch.

Incorrect - we have quite a number of people who are allowed to post
but who are not members, and it's a growing number.  The list may
default to member only posting but there are a couple of sane human
beings behind it who don't randomly throw stuff away for no reason.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:

Re: [PATCH] ARM: Ignore memory tags with invalid data

[Byron Bradley]

On Jan 22, 2008 4:05 AM, Corey Minyard <minyard@acm.org> wrote:
> From: Corey Minyard <minyard@acm.org>
>
> The DNS-323 system has several bogus memory entries in the tag table,
> and it caused the system to crash at startup.  Ignore tag entries that
> are obviously bogus.
>
> Signed-off-by: Corey Minyard <minyard@acm.org>
> ---
>  arch/arm/kernel/setup.c |    7 ++++++-
>  1 files changed, 6 insertions(+), 1 deletions(-)
>
> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> index bf56eb3..dfdb469 100644
> --- a/arch/arm/kernel/setup.c
> +++ b/arch/arm/kernel/setup.c
> @@ -630,7 +630,12 @@ __tagtable(ATAG_CORE, parse_tag_core);
>
>  static int __init parse_tag_mem32(const struct tag *tag)
>  {
> -       if (meminfo.nr_banks >= NR_BANKS) {
> +       /*
> +        * Make sure that the memory size is non-zero, page aligned,
> +        * and that it doesn't overflow the meminfo table.
> +        */
> +       if (meminfo.nr_banks >= NR_BANKS || tag->u.mem.size & ~PAGE_MASK ||
> +           tag->u.mem.size == 0 || tag->u.mem.start & ~PAGE_MASK) {
>                 printk(KERN_WARNING
>                        "Ignoring memory bank 0x%08x size %dKB\n",
>                         tag->u.mem.start, tag->u.mem.size / 1024);
>

[Cc: linux-arm-kernel]

What's the status of this patch? It would be good to see it go in
because the problem it fixes can be seen on a large number of NAS
devices.

Cheers,

-- 
Byron Bradley