* [PATCH 1/1] swapfile: swap_info_get: Check for swap_info[type] == NULL
@ 2011-12-26 11:56 ` Kautuk Consul
0 siblings, 0 replies; 4+ messages in thread
From: Kautuk Consul @ 2011-12-26 11:56 UTC (permalink / raw)
To: Andrew Morton, Cesar Eduardo Barros, KAMEZAWA Hiroyuki,
Eric B Munson, Pekka Enberg
Cc: linux-mm, linux-kernel, Kautuk Consul
From: Kautuk Consul <consul.kautuk@gmail.com>
If the swapfile type encoded within entry.val is corrupted in
such a way that the swap_info[type] == NULL, then the code in
swap_info_get will cause a NULL pointer exception.
Assuming that the code in swap_info_get attempts to validate the
swapfile type by checking its range, another bad_nofile check would
be to check for check whether the swap_info[type] pointer is NULL.
Adding a NULL check for swap_info[type] to be reagrded as a "bad_nofile"
error scenario.
Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
---
mm/swapfile.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index b1cd120..7bdbe91 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -483,6 +483,8 @@ static struct swap_info_struct *swap_info_get(swp_entry_t entry)
if (type >= nr_swapfiles)
goto bad_nofile;
p = swap_info[type];
+ if (!p)
+ goto bad_nofile;
if (!(p->flags & SWP_USED))
goto bad_device;
offset = swp_offset(entry);
--
1.7.6
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH 1/1] swapfile: swap_info_get: Check for swap_info[type] == NULL
@ 2011-12-26 11:56 ` Kautuk Consul
0 siblings, 0 replies; 4+ messages in thread
From: Kautuk Consul @ 2011-12-26 11:56 UTC (permalink / raw)
To: Andrew Morton, Cesar Eduardo Barros, KAMEZAWA Hiroyuki,
Eric B Munson, Pekka Enberg
Cc: linux-mm, linux-kernel, Kautuk Consul
From: Kautuk Consul <consul.kautuk@gmail.com>
If the swapfile type encoded within entry.val is corrupted in
such a way that the swap_info[type] == NULL, then the code in
swap_info_get will cause a NULL pointer exception.
Assuming that the code in swap_info_get attempts to validate the
swapfile type by checking its range, another bad_nofile check would
be to check for check whether the swap_info[type] pointer is NULL.
Adding a NULL check for swap_info[type] to be reagrded as a "bad_nofile"
error scenario.
Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
---
mm/swapfile.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index b1cd120..7bdbe91 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -483,6 +483,8 @@ static struct swap_info_struct *swap_info_get(swp_entry_t entry)
if (type >= nr_swapfiles)
goto bad_nofile;
p = swap_info[type];
+ if (!p)
+ goto bad_nofile;
if (!(p->flags & SWP_USED))
goto bad_device;
offset = swp_offset(entry);
--
1.7.6
--
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^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH 1/1] swapfile: swap_info_get: Check for swap_info[type] == NULL
2011-12-26 11:56 ` Kautuk Consul
@ 2011-12-26 17:45 ` Kautuk Consul
-1 siblings, 0 replies; 4+ messages in thread
From: Kautuk Consul @ 2011-12-26 17:45 UTC (permalink / raw)
To: Andrew Morton, Cesar Eduardo Barros, KAMEZAWA Hiroyuki,
Eric B Munson, Pekka Enberg
Cc: linux-mm, linux-kernel, Kautuk Consul
Hi,
Sorry, please ignore the patch file below.
I made a mistake in understanding the code logic.
I now understand that the first "bad_nofile" validation check
is good enough for checking the validity of the value in the "type" variable.
On Mon, Dec 26, 2011 at 6:56 AM, Kautuk Consul <consul.kautuk@gmail.com> wrote:
> From: Kautuk Consul <consul.kautuk@gmail.com>
>
> If the swapfile type encoded within entry.val is corrupted in
> such a way that the swap_info[type] == NULL, then the code in
> swap_info_get will cause a NULL pointer exception.
>
> Assuming that the code in swap_info_get attempts to validate the
> swapfile type by checking its range, another bad_nofile check would
> be to check for check whether the swap_info[type] pointer is NULL.
>
> Adding a NULL check for swap_info[type] to be reagrded as a "bad_nofile"
> error scenario.
>
> Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
> ---
> mm/swapfile.c | 2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index b1cd120..7bdbe91 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -483,6 +483,8 @@ static struct swap_info_struct *swap_info_get(swp_entry_t entry)
> if (type >= nr_swapfiles)
> goto bad_nofile;
> p = swap_info[type];
> + if (!p)
> + goto bad_nofile;
> if (!(p->flags & SWP_USED))
> goto bad_device;
> offset = swp_offset(entry);
> --
> 1.7.6
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 1/1] swapfile: swap_info_get: Check for swap_info[type] == NULL
@ 2011-12-26 17:45 ` Kautuk Consul
0 siblings, 0 replies; 4+ messages in thread
From: Kautuk Consul @ 2011-12-26 17:45 UTC (permalink / raw)
To: Andrew Morton, Cesar Eduardo Barros, KAMEZAWA Hiroyuki,
Eric B Munson, Pekka Enberg
Cc: linux-mm, linux-kernel, Kautuk Consul
Hi,
Sorry, please ignore the patch file below.
I made a mistake in understanding the code logic.
I now understand that the first "bad_nofile" validation check
is good enough for checking the validity of the value in the "type" variable.
On Mon, Dec 26, 2011 at 6:56 AM, Kautuk Consul <consul.kautuk@gmail.com> wrote:
> From: Kautuk Consul <consul.kautuk@gmail.com>
>
> If the swapfile type encoded within entry.val is corrupted in
> such a way that the swap_info[type] == NULL, then the code in
> swap_info_get will cause a NULL pointer exception.
>
> Assuming that the code in swap_info_get attempts to validate the
> swapfile type by checking its range, another bad_nofile check would
> be to check for check whether the swap_info[type] pointer is NULL.
>
> Adding a NULL check for swap_info[type] to be reagrded as a "bad_nofile"
> error scenario.
>
> Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
> ---
> mm/swapfile.c | 2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index b1cd120..7bdbe91 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -483,6 +483,8 @@ static struct swap_info_struct *swap_info_get(swp_entry_t entry)
> if (type >= nr_swapfiles)
> goto bad_nofile;
> p = swap_info[type];
> + if (!p)
> + goto bad_nofile;
> if (!(p->flags & SWP_USED))
> goto bad_device;
> offset = swp_offset(entry);
> --
> 1.7.6
>
--
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the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
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^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2011-12-26 17:45 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2011-12-26 11:56 [PATCH 1/1] swapfile: swap_info_get: Check for swap_info[type] == NULL Kautuk Consul
2011-12-26 11:56 ` Kautuk Consul
2011-12-26 17:45 ` Kautuk Consul
2011-12-26 17:45 ` Kautuk Consul
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