5.7-stable patches

added patches:
	lib-vdso-provide-sanity-check-for-cycles-again.patch

diff --git a/queue-5.7/lib-vdso-provide-sanity-check-for-cycles-again.patch b/queue-5.7/lib-vdso-provide-sanity-check-for-cycles-again.patch
new file mode 100644 (file)
index 0000000..9739ebe
--- /dev/null
+++ b/queue-5.7/lib-vdso-provide-sanity-check-for-cycles-again.patch
@@ -0,0 +1,77 @@
+From 72ce778007e57e8996b4bebdec738fc5e1145fd2 Mon Sep 17 00:00:00 2001
+From: Thomas Gleixner <tglx@linutronix.de>
+Date: Sat, 6 Jun 2020 23:51:16 +0200
+Subject: lib/vdso: Provide sanity check for cycles (again)
+
+From: Thomas Gleixner <tglx@linutronix.de>
+
+commit 72ce778007e57e8996b4bebdec738fc5e1145fd2 upstream.
+
+The original x86 VDSO implementation checked for the validity of the clock
+source read by testing whether the returned signed cycles value is less
+than zero. This check was also used by the vdso read function to signal
+that the current selected clocksource is not VDSO capable.
+
+During the rework of the VDSO code the check was removed and replaced with
+a check for the clocksource mode being != NONE.
+
+This turned out to be a mistake because the check is necessary for paravirt
+and hyperv clock sources. The reason is that these clock sources have their
+own internal sequence counter to validate the clocksource at the point of
+reading it. This is necessary because the hypervisor can invalidate the
+clocksource asynchronously so a check during the VDSO data update is not
+sufficient. Having a separate indicator for the validity is slower than
+just validating the cycles value. The check for it being negative turned
+out to be the fastest implementation and safe as it would require an uptime
+of ~73 years with a 4GHz counter frequency to result in a false positive.
+
+Add an optional function to validate the cycles with a default
+implementation which allows the compiler to optimize it out for
+architectures which do not require it.
+
+Fixes: 5d51bee725cc ("clocksource: Add common vdso clock mode storage")
+Reported-by: Miklos Szeredi <miklos@szeredi.hu>
+Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
+Tested-by: Miklos Szeredi <mszeredi@redhat.com>
+Cc: stable@vger.kernel.org
+Link: https://lkml.kernel.org/r/20200606221531.963970768@linutronix.de
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ lib/vdso/gettimeofday.c |   11 +++++++++++
+ 1 file changed, 11 insertions(+)
+
+--- a/lib/vdso/gettimeofday.c
++++ b/lib/vdso/gettimeofday.c
+@@ -38,6 +38,13 @@ static inline bool vdso_clocksource_ok(c
+ }
+ #endif
+ 
++#ifndef vdso_cycles_ok
++static inline bool vdso_cycles_ok(u64 cycles)
++{
++      return true;
++}
++#endif
++
+ #ifdef CONFIG_TIME_NS
+ static int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
+                         struct __kernel_timespec *ts)
+@@ -62,6 +69,8 @@ static int do_hres_timens(const struct v
+                       return -1;
+ 
+               cycles = __arch_get_hw_counter(vd->clock_mode);
++              if (unlikely(!vdso_cycles_ok(cycles)))
++                      return -1;
+               ns = vdso_ts->nsec;
+               last = vd->cycle_last;
+               ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
+@@ -130,6 +139,8 @@ static __always_inline int do_hres(const
+                       return -1;
+ 
+               cycles = __arch_get_hw_counter(vd->clock_mode);
++              if (unlikely(!vdso_cycles_ok(cycles)))
++                      return -1;
+               ns = vdso_ts->nsec;
+               last = vd->cycle_last;
+               ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);

diff --git a/queue-5.7/series b/queue-5.7/series
index 78e56fe6d65892928c82979042df7a3eb457eed0..0addd4299e17f15493ba67399c78a25f10696b23 100644 (file)
--- a/queue-5.7/series
+++ b/queue-5.7/series
@@ -253,3 +253,4 @@ bpf-fix-up-bpf_skb_adjust_room-helper-s-skb-csum-set.patch
 s390-bpf-maintain-8-byte-stack-alignment.patch
 kasan-stop-tests-being-eliminated-as-dead-code-with-.patch
 string.h-fix-incompatibility-between-fortify_source-.patch
+lib-vdso-provide-sanity-check-for-cycles-again.patch