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authorDavid Howells <dhowells@redhat.com>2010-08-04 16:59:14 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2010-08-04 11:17:10 -0700
commit694f690d27dadccc8cb9d90532e76593b61fe098 (patch)
treeea641e53ae530d0d3708fbfcab8109cc5e840d21 /kernel
parente75aa85892b2ee78c79edac720868cbef16e62eb (diff)
downloadvexpress-lsk-694f690d27dadccc8cb9d90532e76593b61fe098.tar.gz
CRED: Fix RCU warning due to previous patch fixing __task_cred()'s checks
Commit 8f92054e7ca1 ("CRED: Fix __task_cred()'s lockdep check and banner comment") fixed the lockdep checks on __task_cred(). This has shown up a place in the signalling code where a lock should be held - namely that check_kill_permission() requires its callers to hold the RCU lock. Fix group_send_sig_info() to get the RCU read lock around its call to check_kill_permission(). Without this patch, the following warning can occur: =================================================== [ INFO: suspicious rcu_dereference_check() usage. ] --------------------------------------------------- kernel/signal.c:660 invoked rcu_dereference_check() without protection! ... Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/signal.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 906ae5a1779..bded6518778 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -637,7 +637,7 @@ static inline bool si_fromuser(const struct siginfo *info)
/*
* Bad permissions for sending the signal
- * - the caller must hold at least the RCU read lock
+ * - the caller must hold the RCU read lock
*/
static int check_kill_permission(int sig, struct siginfo *info,
struct task_struct *t)
@@ -1127,11 +1127,14 @@ struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long
/*
* send signal info to all the members of a group
- * - the caller must hold the RCU read lock at least
*/
int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
{
- int ret = check_kill_permission(sig, info, p);
+ int ret;
+
+ rcu_read_lock();
+ ret = check_kill_permission(sig, info, p);
+ rcu_read_unlock();
if (!ret && sig)
ret = do_send_sig_info(sig, info, p, true);