* [PATCH] tmem: Prevent NULL dereference on error case
@ 2012-11-12 3:17 Matthew Daley
0 siblings, 0 replies; 3+ messages in thread
From: Matthew Daley @ 2012-11-12 3:17 UTC (permalink / raw)
To: xen-devel; +Cc: Dan Magenheimer, Matthew Daley
If the client / pool IDs given to tmemc_save_get_next_page are invalid,
the calculation of pagesize will dereference NULL.
Fix this by moving the calculation below the appropriate NULL check.
Signed-off-by: Matthew Daley <mattjd@gmail.com>
diff --git a/xen/common/tmem.c b/xen/common/tmem.c
index 1280537..ec59009 100644
--- a/xen/common/tmem.c
+++ b/xen/common/tmem.c
@@ -2436,10 +2436,13 @@ static NOINLINE int tmemc_save_get_next_page(int cli_id, uint32_t pool_id,
OID oid;
int ret = 0;
struct tmem_handle h;
- unsigned int pagesize = 1 << (pool->pageshift+12);
+ unsigned int pagesize;
if ( pool == NULL || is_ephemeral(pool) )
return -1;
+
+ pagesize = 1 << (pool->pageshift + 12);
+
if ( bufsize < pagesize + sizeof(struct tmem_handle) )
return -ENOMEM;
--
1.7.10.4
^ permalink raw reply related [flat|nested] 3+ messages in thread[parent not found: <<1352690242-28761-1-git-send-email-mattjd@gmail.com>]
* Re: [PATCH] tmem: Prevent NULL dereference on error case
[not found] <<1352690242-28761-1-git-send-email-mattjd@gmail.com>
@ 2012-11-12 16:30 ` Dan Magenheimer
2012-11-12 23:02 ` Matthew Daley
0 siblings, 1 reply; 3+ messages in thread
From: Dan Magenheimer @ 2012-11-12 16:30 UTC (permalink / raw)
To: Matthew Daley, xen-devel; +Cc: Dan Magenheimer
> From: Matthew Daley [mailto:mattjd@gmail.com]
> Subject: [PATCH] tmem: Prevent NULL dereference on error case
>
> If the client / pool IDs given to tmemc_save_get_next_page are invalid,
> the calculation of pagesize will dereference NULL.
>
> Fix this by moving the calculation below the appropriate NULL check.
>
> Signed-off-by: Matthew Daley <mattjd@gmail.com>
Good catch!
Did you see this on an actual save/restore or just by inspection?
This should only happen as a result of a buggy toolstack so I'm
wondering if fixing this hides a toolstack bug. In either case,
this should be fixed in the hypervisor.
Acked-by: Dan Magenheimer <dan.magenheimer@oracle.com>
> diff --git a/xen/common/tmem.c b/xen/common/tmem.c
> index 1280537..ec59009 100644
> --- a/xen/common/tmem.c
> +++ b/xen/common/tmem.c
> @@ -2436,10 +2436,13 @@ static NOINLINE int tmemc_save_get_next_page(int cli_id, uint32_t pool_id,
> OID oid;
> int ret = 0;
> struct tmem_handle h;
> - unsigned int pagesize = 1 << (pool->pageshift+12);
> + unsigned int pagesize;
>
> if ( pool == NULL || is_ephemeral(pool) )
> return -1;
> +
> + pagesize = 1 << (pool->pageshift + 12);
> +
> if ( bufsize < pagesize + sizeof(struct tmem_handle) )
> return -ENOMEM;
>
> --
> 1.7.10.4
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] tmem: Prevent NULL dereference on error case
2012-11-12 16:30 ` Dan Magenheimer
@ 2012-11-12 23:02 ` Matthew Daley
0 siblings, 0 replies; 3+ messages in thread
From: Matthew Daley @ 2012-11-12 23:02 UTC (permalink / raw)
To: Dan Magenheimer; +Cc: xen-devel
On Tue, Nov 13, 2012 at 5:30 AM, Dan Magenheimer
<dan.magenheimer@oracle.com> wrote:
> Did you see this on an actual save/restore or just by inspection?
> This should only happen as a result of a buggy toolstack so I'm
> wondering if fixing this hides a toolstack bug.
Just by inspection of the hypervisor side, so there's no need to worry
about the toolstack.
- Matthew
^ permalink raw reply [flat|nested] 3+ messages in thread
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2012-11-12 3:17 [PATCH] tmem: Prevent NULL dereference on error case Matthew Daley
[not found] <<1352690242-28761-1-git-send-email-mattjd@gmail.com>
2012-11-12 16:30 ` Dan Magenheimer
2012-11-12 23:02 ` Matthew Daley
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