linux-kernel - [PATCH RFC] perf: fix find_swevent

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 13 May 2010 11:25:56 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...e.hu, fweisbec@...il.com, a.p.zijlstra@...llo.nl,
	paulus@...ba.org, acme@...hat.com
Subject: [PATCH RFC] perf: fix find_swevent_head() RCU lockdep splat

This commit guesses at the perf_cpu_context locking design and deploys
an rcu_dereference_check() accordingly.  The design appears to require
that a given CPU be accessing its own per_cpu_context or that it be
traversing under RCU protection.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>

 perf_event.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index a4fa381..002791c 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -4074,7 +4074,9 @@ find_swevent_head(struct perf_cpu_context *ctx, u64 type, u32 event_id)
 
 	hash = swevent_hash(type, event_id);
 
-	hlist = rcu_dereference(ctx->swevent_hlist);
+	hlist = rcu_dereference_check(ctx->swevent_hlist,
+				      rcu_read_lock_held() ||
+				      ctx == &__get_cpu_var(perf_cpu_context));
 	if (!hlist)
 		return NULL;
 
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/