linux-stable.git/kernel, branch v5.12.9

bpf, offload: Reorder offload callback 'prepare' in verifier

2021-06-03T07:09:49+00:00

[ Upstream commit ceb11679d9fcf3fdb358a310a38760fcbe9b63ed ]

Commit 4976b718c355 ("bpf: Introduce pseudo_btf_id") switched the
order of resolve_pseudo_ldimm(), in which some pseudo instructions
are rewritten. Thus those rewritten instructions cannot be passed
to driver via 'prepare' offload callback.

Reorder the 'prepare' offload callback to fix it.

Fixes: 4976b718c355 ("bpf: Introduce pseudo_btf_id")
Signed-off-by: Yinjun Zhang 
Signed-off-by: Simon Horman 
Signed-off-by: Daniel Borkmann 
Acked-by: Song Liu 
Link: https://lore.kernel.org/bpf/20210520085834.15023-1-simon.horman@netronome.com
Signed-off-by: Sasha Levin

seccomp: Refactor notification handler to prepare for new semantics

2021-06-03T07:09:28+00:00

commit ddc473916955f7710d1eb17c1273d91c8622a9fe upstream.

This refactors the user notification code to have a do / while loop around
the completion condition. This has a small change in semantic, in that
previously we ignored addfd calls upon wakeup if the notification had been
responded to, but instead with the new change we check for an outstanding
addfd calls prior to returning to userspace.

Rodrigo Campos also identified a bug that can result in addfd causing
an early return, when the supervisor didn't actually handle the
syscall [1].

[1]: https://lore.kernel.org/lkml/20210413160151.3301-1-rodrigo@kinvolk.io/

Fixes: 7cf97b125455 ("seccomp: Introduce addfd ioctl to seccomp user notifier")
Signed-off-by: Sargun Dhillon 
Acked-by: Tycho Andersen 
Acked-by: Christian Brauner 
Signed-off-by: Kees Cook 
Tested-by: Rodrigo Campos 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210517193908.3113-3-sargun@sargun.me
Signed-off-by: Greg Kroah-Hartman

bpf: No need to simulate speculative domain for immediates

2021-05-28T11:18:52+00:00

commit a7036191277f9fa68d92f2071ddc38c09b1e5ee5 upstream.

In 801c6058d14a ("bpf: Fix leakage of uninitialized bpf stack under
speculation") we replaced masking logic with direct loads of immediates
if the register is a known constant. Given in this case we do not apply
any masking, there is also no reason for the operation to be truncated
under the speculative domain.

Therefore, there is also zero reason for the verifier to branch-off and
simulate this case, it only needs to do it for unknown but bounded scalars.
As a side-effect, this also enables few test cases that were previously
rejected due to simulation under zero truncation.

Signed-off-by: Daniel Borkmann 
Reviewed-by: Piotr Krysiuk 
Acked-by: Alexei Starovoitov 
Signed-off-by: Greg Kroah-Hartman

bpf: Fix mask direction swap upon off reg sign change

2021-05-28T11:18:52+00:00

commit bb01a1bba579b4b1c5566af24d95f1767859771e upstream.

Masking direction as indicated via mask_to_left is considered to be
calculated once and then used to derive pointer limits. Thus, this
needs to be placed into bpf_sanitize_info instead so we can pass it
to sanitize_ptr_alu() call after the pointer move. Piotr noticed a
corner case where the off reg causes masking direction change which
then results in an incorrect final aux->alu_limit.

Fixes: 7fedb63a8307 ("bpf: Tighten speculative pointer arithmetic mask")
Reported-by: Piotr Krysiuk 
Signed-off-by: Daniel Borkmann 
Reviewed-by: Piotr Krysiuk 
Acked-by: Alexei Starovoitov 
Signed-off-by: Greg Kroah-Hartman

bpf: Wrap aux data inside bpf_sanitize_info container

2021-05-28T11:18:52+00:00

commit 3d0220f6861d713213b015b582e9f21e5b28d2e0 upstream.

Add a container structure struct bpf_sanitize_info which holds
the current aux info, and update call-sites to sanitize_ptr_alu()
to pass it in. This is needed for passing in additional state
later on.

Signed-off-by: Daniel Borkmann 
Reviewed-by: Piotr Krysiuk 
Acked-by: Alexei Starovoitov 
Signed-off-by: Greg Kroah-Hartman

kcsan: Fix debugfs initcall return type

2021-05-26T10:59:11+00:00

commit 976aac5f882989e4f6c1b3a7224819bf0e801c6a upstream.

clang with CONFIG_LTO_CLANG points out that an initcall function should
return an 'int' due to the changes made to the initcall macros in commit
3578ad11f3fb ("init: lto: fix PREL32 relocations"):

kernel/kcsan/debugfs.c:274:15: error: returning 'void' from a function with incompatible result type 'int'
late_initcall(kcsan_debugfs_init);
~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
include/linux/init.h:292:46: note: expanded from macro 'late_initcall'
 #define late_initcall(fn)               __define_initcall(fn, 7)

Fixes: e36299efe7d7 ("kcsan, debugfs: Move debugfs file creation out of early init")
Cc: stable 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Marco Elver 
Reviewed-by: Nathan Chancellor 
Reviewed-by: Miguel Ojeda 
Signed-off-by: Arnd Bergmann 
Signed-off-by: Paul E. McKenney 
Signed-off-by: Greg Kroah-Hartman

locking/mutex: clear MUTEX_FLAGS if wait_list is empty due to signal

2021-05-26T10:59:05+00:00

[ Upstream commit 3a010c493271f04578b133de977e0e5dd2848cea ]

When a interruptible mutex locker is interrupted by a signal
without acquiring this lock and removed from the wait queue.
if the mutex isn't contended enough to have a waiter
put into the wait queue again, the setting of the WAITER
bit will force mutex locker to go into the slowpath to
acquire the lock every time, so if the wait queue is empty,
the WAITER bit need to be clear.

Fixes: 040a0a371005 ("mutex: Add support for wound/wait style locks")
Suggested-by: Peter Zijlstra 
Signed-off-by: Zqiang 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20210517034005.30828-1-qiang.zhang@windriver.com
Signed-off-by: Sasha Levin

locking/lockdep: Correct calling tracepoints

2021-05-26T10:59:05+00:00

[ Upstream commit 89e70d5c583c55088faa2201d397ee30a15704aa ]

The commit eb1f00237aca ("lockdep,trace: Expose tracepoints") reverses
tracepoints for lock_contended() and lock_acquired(), thus the ftrace
log shows the wrong locking sequence that "acquired" event is prior to
"contended" event:

  -0       [001] d.s3 20803.501685: lock_acquire: 0000000008b91ab4 &sg_policy->update_lock
  -0       [001] d.s3 20803.501686: lock_acquired: 0000000008b91ab4 &sg_policy->update_lock
  -0       [001] d.s3 20803.501689: lock_contended: 0000000008b91ab4 &sg_policy->update_lock
  -0       [001] d.s3 20803.501690: lock_release: 0000000008b91ab4 &sg_policy->update_lock

This patch fixes calling tracepoints for lock_contended() and
lock_acquired().

Fixes: eb1f00237aca ("lockdep,trace: Expose tracepoints")
Signed-off-by: Leo Yan 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20210512120937.90211-1-leo.yan@linaro.org
Signed-off-by: Sasha Levin

ptrace: make ptrace() fail if the tracee changed its pid unexpectedly

2021-05-26T10:59:05+00:00

[ Upstream commit dbb5afad100a828c97e012c6106566d99f041db6 ]

Suppose we have 2 threads, the group-leader L and a sub-theread T,
both parked in ptrace_stop(). Debugger tries to resume both threads
and does

	ptrace(PTRACE_CONT, T);
	ptrace(PTRACE_CONT, L);

If the sub-thread T execs in between, the 2nd PTRACE_CONT doesn not
resume the old leader L, it resumes the post-exec thread T which was
actually now stopped in PTHREAD_EVENT_EXEC. In this case the
PTHREAD_EVENT_EXEC event is lost, and the tracer can't know that the
tracee changed its pid.

This patch makes ptrace() fail in this case until debugger does wait()
and consumes PTHREAD_EVENT_EXEC which reports old_pid. This affects all
ptrace requests except the "asynchronous" PTRACE_INTERRUPT/KILL.

The patch doesn't add the new PTRACE_ option to not complicate the API,
and I _hope_ this won't cause any noticeable regression:

	- If debugger uses PTRACE_O_TRACEEXEC and the thread did an exec
	  and the tracer does a ptrace request without having consumed
	  the exec event, it's 100% sure that the thread the ptracer
	  thinks it is targeting does not exist anymore, or isn't the
	  same as the one it thinks it is targeting.

	- To some degree this patch adds nothing new. In the scenario
	  above ptrace(L) can fail with -ESRCH if it is called after the
	  execing sub-thread wakes the leader up and before it "steals"
	  the leader's pid.

Test-case:

	#include 
	#include 
	#include 
	#include 
	#include 
	#include 
	#include 
	#include 

	void *tf(void *arg)
	{
		execve("/usr/bin/true", NULL, NULL);
		assert(0);

		return NULL;
	}

	int main(void)
	{
		int leader = fork();
		if (!leader) {
			kill(getpid(), SIGSTOP);

			pthread_t th;
			pthread_create(&th, NULL, tf, NULL);
			for (;;)
				pause();

			return 0;
		}

		waitpid(leader, NULL, WSTOPPED);

		ptrace(PTRACE_SEIZE, leader, 0,
				PTRACE_O_TRACECLONE | PTRACE_O_TRACEEXEC);
		waitpid(leader, NULL, 0);

		ptrace(PTRACE_CONT, leader, 0,0);
		waitpid(leader, NULL, 0);

		int status, thread = waitpid(-1, &status, 0);
		assert(thread > 0 && thread != leader);
		assert(status == 0x80137f);

		ptrace(PTRACE_CONT, thread, 0,0);
		/*
		 * waitid() because waitpid(leader, &status, WNOWAIT) does not
		 * report status. Why ????
		 *
		 * Why WEXITED? because we have another kernel problem connected
		 * to mt-exec.
		 */
		siginfo_t info;
		assert(waitid(P_PID, leader, &info, WSTOPPED|WEXITED|WNOWAIT) == 0);
		assert(info.si_pid == leader && info.si_status == 0x0405);

		/* OK, it sleeps in ptrace(PTRACE_EVENT_EXEC == 0x04) */
		assert(ptrace(PTRACE_CONT, leader, 0,0) == -1);
		assert(errno == ESRCH);

		assert(leader == waitpid(leader, &status, WNOHANG));
		assert(status == 0x04057f);

		assert(ptrace(PTRACE_CONT, leader, 0,0) == 0);

		return 0;
	}

Signed-off-by: Oleg Nesterov 
Reported-by: Simon Marchi 
Acked-by: "Eric W. Biederman" 
Acked-by: Pedro Alves 
Acked-by: Simon Marchi 
Acked-by: Jan Kratochvil 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

alarmtimer: Check RTC features instead of ops

2021-05-19T08:56:41+00:00

commit e09784a8a751e539dffc94d43bc917b0ac1e934a upstream.

RTC drivers used to leave .set_alarm() NULL in order to signal the RTC
device doesn't support alarms. The drivers are now clearing the
RTC_FEATURE_ALARM bit for that purpose in order to keep the rtc_class_ops
structure const. So now, .set_alarm() is set unconditionally and this
possibly causes the alarmtimer code to select an RTC device that doesn't
support alarms.

Test RTC_FEATURE_ALARM instead of relying on ops->set_alarm to determine
whether alarms are available.

Fixes: 7ae41220ef58 ("rtc: introduce features bitfield")
Signed-off-by: Alexandre Belloni 
Signed-off-by: Thomas Gleixner 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210511014516.563031-1-alexandre.belloni@bootlin.com
Signed-off-by: Greg Kroah-Hartman