From: Jiri Olsa <jolsa@kernel.org>
To: Fenghua Yu <fenghua.yu@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Peter Zijlstra <peterz@infradead.org>,
Mike Galbraith <efault@gmx.de>, Shaohua Li <shli@fb.com>,
lkml <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH] x86/intel_rdt: Fix locking in rdtgroup_schemata_write
Date: Tue, 11 Apr 2017 09:14:46 +0200 [thread overview]
Message-ID: <20170411071446.15241-1-jolsa@kernel.org> (raw)
Currently we release the schemata lock before we free the
resource's temporary tmp_cbms allocation, which could be
already used another concurrent access and crashed like:
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: rdtgroup_schemata_write+0x2d1/0x460
...
SNIP
...
rdtgroup_file_write+0x1b/0x30
kernfs_fop_write+0xe0/0x160
vfs_write+0xbd/0x1e0
SyS_write+0x7f/0xe0
system_call_fastpath+0x16/0x1b
Moving the unlock after the release code.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Shaohua Li <shli@fb.com>
---
arch/x86/kernel/cpu/intel_rdt_schemata.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/intel_rdt_schemata.c b/arch/x86/kernel/cpu/intel_rdt_schemata.c
index f369cb8db0d5..badd2b31a560 100644
--- a/arch/x86/kernel/cpu/intel_rdt_schemata.c
+++ b/arch/x86/kernel/cpu/intel_rdt_schemata.c
@@ -200,11 +200,11 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
}
out:
- rdtgroup_kn_unlock(of->kn);
for_each_enabled_rdt_resource(r) {
kfree(r->tmp_cbms);
r->tmp_cbms = NULL;
}
+ rdtgroup_kn_unlock(of->kn);
return ret ?: nbytes;
}
--
2.9.3
next reply other threads:[~2017-04-11 7:14 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-11 7:14 Jiri Olsa [this message]
2017-04-11 8:03 ` [tip:x86/urgent] x86/intel_rdt: Fix locking in rdtgroup_schemata_write() tip-bot for Jiri Olsa
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