* [PATCH] x86/intel_rdt: Fix locking in rdtgroup_schemata_write
@ 2017-04-11 7:14 Jiri Olsa
2017-04-11 8:03 ` [tip:x86/urgent] x86/intel_rdt: Fix locking in rdtgroup_schemata_write() tip-bot for Jiri Olsa
0 siblings, 1 reply; 2+ messages in thread
From: Jiri Olsa @ 2017-04-11 7:14 UTC (permalink / raw)
To: Fenghua Yu
Cc: Peter Zijlstra, Peter Zijlstra, Mike Galbraith, Shaohua Li, lkml,
Ingo Molnar, Thomas Gleixner
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [tip:x86/urgent] x86/intel_rdt: Fix locking in rdtgroup_schemata_write()
2017-04-11 7:14 [PATCH] x86/intel_rdt: Fix locking in rdtgroup_schemata_write Jiri Olsa
@ 2017-04-11 8:03 ` tip-bot for Jiri Olsa
0 siblings, 0 replies; 2+ messages in thread
From: tip-bot for Jiri Olsa @ 2017-04-11 8:03 UTC (permalink / raw)
To: linux-tip-commits
Cc: tglx, shli, hpa, mingo, peterz, jolsa, fenghua.yu, linux-kernel,
efault, a.p.zijlstra
Commit-ID: 7f00f388712b29005782bad7e4b25942620f3b9c
Gitweb: http://git.kernel.org/tip/7f00f388712b29005782bad7e4b25942620f3b9c
Author: Jiri Olsa <jolsa@kernel.org>
AuthorDate: Tue, 11 Apr 2017 09:14:46 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 11 Apr 2017 09:48:12 +0200
x86/intel_rdt: Fix locking in rdtgroup_schemata_write()
The schemata lock is released before freeing the resource's temporary
tmp_cbms allocation. That's racy versus another write which allocates and
uses new temporary storage, resulting in memory leaks, freeing in use
memory, double a free or any combination of those.
Move the unlock after the release code.
Fixes: 60ec2440c63d ("x86/intel_rdt: Add schemata file")
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>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20170411071446.15241-1-jolsa@kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
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 f369cb8..badd2b3 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;
}
^ permalink raw reply related [flat|nested] 2+ messages in thread
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