diff options
author | Thomas Gleixner <tglx@linutronix.de> | 2019-04-14 19:51:06 +0200 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-04-27 09:36:38 +0200 |
commit | 5680b0635cdab1a1afb4f2078226584e008008b0 (patch) | |
tree | 9e449c9048863a09957512ee8db519fa045a74f9 /arch/x86/kernel/process.c | |
parent | 90e17512f1e43a67008082d0380bdc8a689c6c9b (diff) | |
download | linux-stable-5680b0635cdab1a1afb4f2078226584e008008b0.tar.gz linux-stable-5680b0635cdab1a1afb4f2078226584e008008b0.tar.bz2 linux-stable-5680b0635cdab1a1afb4f2078226584e008008b0.zip |
x86/speculation: Prevent deadlock on ssb_state::lock
commit 2f5fb19341883bb6e37da351bc3700489d8506a7 upstream.
Mikhail reported a lockdep splat related to the AMD specific ssb_state
lock:
CPU0 CPU1
lock(&st->lock);
local_irq_disable();
lock(&(&sighand->siglock)->rlock);
lock(&st->lock);
<Interrupt>
lock(&(&sighand->siglock)->rlock);
*** DEADLOCK ***
The connection between sighand->siglock and st->lock comes through seccomp,
which takes st->lock while holding sighand->siglock.
Make sure interrupts are disabled when __speculation_ctrl_update() is
invoked via prctl() -> speculation_ctrl_update(). Add a lockdep assert to
catch future offenders.
Fixes: 1f50ddb4f418 ("x86/speculation: Handle HT correctly on AMD")
Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Cc: Thomas Lendacky <thomas.lendacky@amd.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1904141948200.4917@nanos.tec.linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86/kernel/process.c')
-rw-r--r-- | arch/x86/kernel/process.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 7d31192296a8..b8b08e61ac73 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -411,6 +411,8 @@ static __always_inline void __speculation_ctrl_update(unsigned long tifp, u64 msr = x86_spec_ctrl_base; bool updmsr = false; + lockdep_assert_irqs_disabled(); + /* * If TIF_SSBD is different, select the proper mitigation * method. Note that if SSBD mitigation is disabled or permanentely @@ -462,10 +464,12 @@ static unsigned long speculation_ctrl_update_tif(struct task_struct *tsk) void speculation_ctrl_update(unsigned long tif) { + unsigned long flags; + /* Forced update. Make sure all relevant TIF flags are different */ - preempt_disable(); + local_irq_save(flags); __speculation_ctrl_update(~tif, tif); - preempt_enable(); + local_irq_restore(flags); } /* Called from seccomp/prctl update */ |