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Old 06-29-2011, 11:06 AM
Ming Lei
 
Default UBUNTU: SAUCE: fix yama_ptracer_del lockdep warning(v1)

yama_ptracer_del can be called in softirq context, so
ptracer_relations_lock may be held in softirq context.

This patch replaces spin_[un]lock with spin_[un]lock_bh for
&ptracer_relations_lock to fix reported lockdep warning and
avoid possible dealock.

SRU Justification:

Impact:
- lockdep warning is triggered if lockdep config options are
enabled
- probably deadlock can be produced in yama_ptracer_del path

Fix:
- After applying the patch, lockdep warning is fixefd

BugLink: http://bugs.launchpad.net/bugs/791019

Signed-off-by: Ming Lei <ming.lei@canonical.com>
---
security/yama/yama_lsm.c | 12 ++++++------
1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index 7c3591a..b200e33 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -46,7 +46,7 @@ static int yama_ptracer_add(struct task_struct *tracer,
struct ptrace_relation *entry, *relation = NULL;

added = kmalloc(sizeof(*added), GFP_KERNEL);
- spin_lock(&ptracer_relations_lock);
+ spin_lock_bh(&ptracer_relations_lock);
list_for_each_entry(entry, &ptracer_relations, node)
if (entry->tracee == tracee) {
relation = entry;
@@ -64,7 +64,7 @@ static int yama_ptracer_add(struct task_struct *tracer,
relation->tracer = tracer;

unlock_out:
- spin_unlock(&ptracer_relations_lock);
+ spin_unlock_bh(&ptracer_relations_lock);
if (added && added != relation)
kfree(added);

@@ -82,7 +82,7 @@ static void yama_ptracer_del(struct task_struct *tracer,
struct ptrace_relation *relation;
struct list_head *list, *safe;

- spin_lock(&ptracer_relations_lock);
+ spin_lock_bh(&ptracer_relations_lock);
list_for_each_safe(list, safe, &ptracer_relations) {
relation = list_entry(list, struct ptrace_relation, node);
if (relation->tracee == tracee ||
@@ -91,7 +91,7 @@ static void yama_ptracer_del(struct task_struct *tracer,
kfree(relation);
}
}
- spin_unlock(&ptracer_relations_lock);
+ spin_unlock_bh(&ptracer_relations_lock);
}

/**
@@ -205,7 +205,7 @@ static int ptracer_exception_found(struct task_struct *tracer,
struct ptrace_relation *relation;
struct task_struct *parent = NULL;

- spin_lock(&ptracer_relations_lock);
+ spin_lock_bh(&ptracer_relations_lock);

rcu_read_lock();
read_lock(&tasklist_lock);
@@ -221,7 +221,7 @@ static int ptracer_exception_found(struct task_struct *tracer,

if (task_is_descendant(parent, tracer))
rc = 1;
- spin_unlock(&ptracer_relations_lock);
+ spin_unlock_bh(&ptracer_relations_lock);

return rc;
}
--
1.7.4.1



--
Ming Lei

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