* [PATCH] clone3: fix cgroup argument sanity check
@ 2020-04-12 20:25 Eugene Syromiatnikov
2020-04-12 21:10 ` Christian Brauner
2020-04-15 12:38 ` Christian Brauner
0 siblings, 2 replies; 3+ messages in thread
From: Eugene Syromiatnikov @ 2020-04-12 20:25 UTC (permalink / raw)
To: linux-kernel, Christian Brauner
Cc: Andrew Morton, Ingo Molnar, Tejun Heo, Oleg Nesterov,
Johannes Weiner, Li Zefan, Peter Zijlstra, cgroups,
Dmitry V. Levin
Checking that cgroup field value of struct clone_args is less than 0
is useless, as it is defined as unsigned 64-bit integer. Moreover,
it doesn't catch the situations where its higher bits are lost during
the assignment to the cgroup field of the cgroup field of the internal
struct kernel_clone_args (where it is declared as signed 32-bit
integer), so it is still possible to pass garbage there. A check
against INT_MAX solves both these issues.
Fixes: ef2c41cf38a7559b ("clone3: allow spawning processes into cgroups")
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
---
kernel/fork.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/fork.c b/kernel/fork.c
index 4385f3d..b4f7775 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2631,7 +2631,7 @@ noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
!valid_signal(args.exit_signal)))
return -EINVAL;
- if ((args.flags & CLONE_INTO_CGROUP) && args.cgroup < 0)
+ if ((args.flags & CLONE_INTO_CGROUP) && args.cgroup > INT_MAX)
return -EINVAL;
*kargs = (struct kernel_clone_args){
--
2.1.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] clone3: fix cgroup argument sanity check
2020-04-12 20:25 [PATCH] clone3: fix cgroup argument sanity check Eugene Syromiatnikov
@ 2020-04-12 21:10 ` Christian Brauner
2020-04-15 12:38 ` Christian Brauner
1 sibling, 0 replies; 3+ messages in thread
From: Christian Brauner @ 2020-04-12 21:10 UTC (permalink / raw)
To: Eugene Syromiatnikov
Cc: linux-kernel, Christian Brauner, Andrew Morton, Ingo Molnar,
Tejun Heo, Oleg Nesterov, Johannes Weiner, Li Zefan,
Peter Zijlstra, cgroups, Dmitry V. Levin
On Sun, Apr 12, 2020 at 10:25:33PM +0200, Eugene Syromiatnikov wrote:
> Checking that cgroup field value of struct clone_args is less than 0
> is useless, as it is defined as unsigned 64-bit integer. Moreover,
> it doesn't catch the situations where its higher bits are lost during
> the assignment to the cgroup field of the cgroup field of the internal
> struct kernel_clone_args (where it is declared as signed 32-bit
> integer), so it is still possible to pass garbage there. A check
> against INT_MAX solves both these issues.
>
> Fixes: ef2c41cf38a7559b ("clone3: allow spawning processes into cgroups")
> Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
Thanks, will queue for rc2 unless I hear objections.
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] clone3: fix cgroup argument sanity check
2020-04-12 20:25 [PATCH] clone3: fix cgroup argument sanity check Eugene Syromiatnikov
2020-04-12 21:10 ` Christian Brauner
@ 2020-04-15 12:38 ` Christian Brauner
1 sibling, 0 replies; 3+ messages in thread
From: Christian Brauner @ 2020-04-15 12:38 UTC (permalink / raw)
To: Eugene Syromiatnikov
Cc: linux-kernel, Christian Brauner, Andrew Morton, Ingo Molnar,
Tejun Heo, Oleg Nesterov, Johannes Weiner, Li Zefan,
Peter Zijlstra, cgroups, Dmitry V. Levin
On Sun, Apr 12, 2020 at 10:25:33PM +0200, Eugene Syromiatnikov wrote:
> Checking that cgroup field value of struct clone_args is less than 0
> is useless, as it is defined as unsigned 64-bit integer. Moreover,
> it doesn't catch the situations where its higher bits are lost during
> the assignment to the cgroup field of the cgroup field of the internal
> struct kernel_clone_args (where it is declared as signed 32-bit
> integer), so it is still possible to pass garbage there. A check
> against INT_MAX solves both these issues.
>
> Fixes: ef2c41cf38a7559b ("clone3: allow spawning processes into cgroups")
> Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
> Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Applied, thanks!
Christian
^ permalink raw reply [flat|nested] 3+ messages in thread
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