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Subject[PATCH v2 6/8] core: allow setrlimit to non-current tasks
Date
Add locking to allow setrlimit accept task parameter other than
current.

Namely, lock tasklist_lock for read and check whether the task
structure has sighand non-null. Do all the signal processing under
that lock still held. We do this only for non-current tasks.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
---
kernel/sys.c | 10 +++++++++-
1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/kernel/sys.c b/kernel/sys.c
index 655dd7b..791b5c5 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1247,9 +1247,16 @@ int setrlimit(struct task_struct *tsk, unsigned int resource,
if (resource == RLIMIT_NOFILE && new_rlim->rlim_max > sysctl_nr_open)
return -EPERM;

+ /* protect tsk->signal and tsk->sighand from disappearing */
+ read_lock(&tasklist_lock);
+ if (!tsk->sighand) {
+ retval = -ESRCH;
+ goto out;
+ }
+
retval = security_task_setrlimit(tsk, resource, new_rlim);
if (retval)
- return retval;
+ goto out;

if (resource == RLIMIT_CPU && new_rlim->rlim_cur == 0) {
/*
@@ -1284,6 +1291,7 @@ int setrlimit(struct task_struct *tsk, unsigned int resource,

update_rlimit_cpu(tsk, new_rlim->rlim_cur);
out:
+ read_unlock(&tasklist_lock);
return retval;
}

--
1.6.3.3


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