December 2023 - Linux-stable-mirror

[for-linus][PATCH 8/8] ring-buffer: Test last update in 32bit version of __rb_time_read()

by Steven Rostedt

From: "Steven Rostedt (Google)" <rostedt(a)goodmis.org> Since 64 bit cmpxchg() is very expensive on 32bit architectures, the timestamp used by the ring buffer does some interesting tricks to be able to still have an atomic 64 bit number. It originally just used 60 bits and broke it up into two 32 bit words where the extra 2 bits were used for synchronization. But this was not enough for all use cases, and all 64 bits were required. The 32bit version of the ring buffer timestamp was then broken up into 3 32bit words using the same counter trick. But one update was not done. The check to see if the read operation was done without interruption only checked the first two words and not last one (like it had before this update). Fix it by making sure all three updates happen without interruption by comparing the initial counter with the last updated counter. Link: https://lore.kernel.org/linux-trace-kernel/20231206100050.3100b7bb@gandalf.… Cc: stable(a)vger.kernel.org Cc: Masami Hiramatsu <mhiramat(a)kernel.org> Cc: Mark Rutland <mark.rutland(a)arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com> Fixes: f03f2abce4f39 ("ring-buffer: Have 32 bit time stamps use all 64 bits") Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> --- kernel/trace/ring_buffer.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index a6da2d765c78..8d2a4f00eca9 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -644,8 +644,8 @@ static inline bool __rb_time_read(rb_time_t *t, u64 *ret, unsigned long *cnt) *cnt = rb_time_cnt(top); - /* If top and bottom counts don't match, this interrupted a write */ - if (*cnt != rb_time_cnt(bottom)) + /* If top and msb counts don't match, this interrupted a write */ + if (*cnt != rb_time_cnt(msb)) return false; /* The shift to msb will lose its cnt bits */ -- 2.42.0

1 year, 6 months

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[for-linus][PATCH 7/8] ring-buffer: Force absolute timestamp on discard of event

by Steven Rostedt

From: "Steven Rostedt (Google)" <rostedt(a)goodmis.org> There's a race where if an event is discarded from the ring buffer and an interrupt were to happen at that time and insert an event, the time stamp is still used from the discarded event as an offset. This can screw up the timings. If the event is going to be discarded, set the "before_stamp" to zero. When a new event comes in, it compares the "before_stamp" with the "write_stamp" and if they are not equal, it will insert an absolute timestamp. This will prevent the timings from getting out of sync due to the discarded event. Link: https://lore.kernel.org/linux-trace-kernel/20231206100244.5130f9b3@gandalf.… Cc: stable(a)vger.kernel.org Cc: Masami Hiramatsu <mhiramat(a)kernel.org> Cc: Mark Rutland <mark.rutland(a)arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com> Fixes: 6f6be606e763f ("ring-buffer: Force before_stamp and write_stamp to be different on discard") Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> --- kernel/trace/ring_buffer.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 43cc47d7faaf..a6da2d765c78 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -3030,22 +3030,19 @@ rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer, local_read(&bpage->write) & ~RB_WRITE_MASK; unsigned long event_length = rb_event_length(event); + /* + * For the before_stamp to be different than the write_stamp + * to make sure that the next event adds an absolute + * value and does not rely on the saved write stamp, which + * is now going to be bogus. + */ + rb_time_set(&cpu_buffer->before_stamp, 0); + /* Something came in, can't discard */ if (!rb_time_cmpxchg(&cpu_buffer->write_stamp, write_stamp, write_stamp - delta)) return false; - /* - * It's possible that the event time delta is zero - * (has the same time stamp as the previous event) - * in which case write_stamp and before_stamp could - * be the same. In such a case, force before_stamp - * to be different than write_stamp. It doesn't - * matter what it is, as long as its different. - */ - if (!delta) - rb_time_set(&cpu_buffer->before_stamp, 0); - /* * If an event were to come in now, it would see that the * write_stamp and the before_stamp are different, and assume -- 2.42.0

1 year, 6 months

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[for-linus][PATCH 6/8] tracing: Fix a possible race when disabling buffered events

by Steven Rostedt

From: Petr Pavlu <petr.pavlu(a)suse.com> Function trace_buffered_event_disable() is responsible for freeing pages backing buffered events and this process can run concurrently with trace_event_buffer_lock_reserve(). The following race is currently possible: * Function trace_buffered_event_disable() is called on CPU 0. It increments trace_buffered_event_cnt on each CPU and waits via synchronize_rcu() for each user of trace_buffered_event to complete. * After synchronize_rcu() is finished, function trace_buffered_event_disable() has the exclusive access to trace_buffered_event. All counters trace_buffered_event_cnt are at 1 and all pointers trace_buffered_event are still valid. * At this point, on a different CPU 1, the execution reaches trace_event_buffer_lock_reserve(). The function calls preempt_disable_notrace() and only now enters an RCU read-side critical section. The function proceeds and reads a still valid pointer from trace_buffered_event[CPU1] into the local variable "entry". However, it doesn't yet read trace_buffered_event_cnt[CPU1] which happens later. * Function trace_buffered_event_disable() continues. It frees trace_buffered_event[CPU1] and decrements trace_buffered_event_cnt[CPU1] back to 0. * Function trace_event_buffer_lock_reserve() continues. It reads and increments trace_buffered_event_cnt[CPU1] from 0 to 1. This makes it believe that it can use the "entry" that it already obtained but the pointer is now invalid and any access results in a use-after-free. Fix the problem by making a second synchronize_rcu() call after all trace_buffered_event values are set to NULL. This waits on all potential users in trace_event_buffer_lock_reserve() that still read a previous pointer from trace_buffered_event. Link: https://lore.kernel.org/all/20231127151248.7232-2-petr.pavlu@suse.com/ Link: https://lkml.kernel.org/r/20231205161736.19663-4-petr.pavlu@suse.com Cc: stable(a)vger.kernel.org Fixes: 0fc1b09ff1ff ("tracing: Use temp buffer when filtering events") Signed-off-by: Petr Pavlu <petr.pavlu(a)suse.com> Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> --- kernel/trace/trace.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index ef72354f61ce..fbcd3bafb93e 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2791,13 +2791,17 @@ void trace_buffered_event_disable(void) free_page((unsigned long)per_cpu(trace_buffered_event, cpu)); per_cpu(trace_buffered_event, cpu) = NULL; } + /* - * Make sure trace_buffered_event is NULL before clearing - * trace_buffered_event_cnt. + * Wait for all CPUs that potentially started checking if they can use + * their event buffer only after the previous synchronize_rcu() call and + * they still read a valid pointer from trace_buffered_event. It must be + * ensured they don't see cleared trace_buffered_event_cnt else they + * could wrongly decide to use the pointed-to buffer which is now freed. */ - smp_wmb(); + synchronize_rcu(); - /* Do the work on each cpu */ + /* For each CPU, relinquish the buffer */ on_each_cpu_mask(tracing_buffer_mask, enable_trace_buffered_event, NULL, true); } -- 2.42.0

1 year, 6 months

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[for-linus][PATCH 4/8] tracing: Fix incomplete locking when disabling buffered events

by Steven Rostedt

From: Petr Pavlu <petr.pavlu(a)suse.com> The following warning appears when using buffered events: [ 203.556451] WARNING: CPU: 53 PID: 10220 at kernel/trace/ring_buffer.c:3912 ring_buffer_discard_commit+0x2eb/0x420 [...] [ 203.670690] CPU: 53 PID: 10220 Comm: stress-ng-sysin Tainted: G E 6.7.0-rc2-default #4 56e6d0fcf5581e6e51eaaecbdaec2a2338c80f3a [ 203.670704] Hardware name: Intel Corp. GROVEPORT/GROVEPORT, BIOS GVPRCRB1.86B.0016.D04.1705030402 05/03/2017 [ 203.670709] RIP: 0010:ring_buffer_discard_commit+0x2eb/0x420 [ 203.735721] Code: 4c 8b 4a 50 48 8b 42 48 49 39 c1 0f 84 b3 00 00 00 49 83 e8 01 75 b1 48 8b 42 10 f0 ff 40 08 0f 0b e9 fc fe ff ff f0 ff 47 08 <0f> 0b e9 77 fd ff ff 48 8b 42 10 f0 ff 40 08 0f 0b e9 f5 fe ff ff [ 203.735734] RSP: 0018:ffffb4ae4f7b7d80 EFLAGS: 00010202 [ 203.735745] RAX: 0000000000000000 RBX: ffffb4ae4f7b7de0 RCX: ffff8ac10662c000 [ 203.735754] RDX: ffff8ac0c750be00 RSI: ffff8ac10662c000 RDI: ffff8ac0c004d400 [ 203.781832] RBP: ffff8ac0c039cea0 R08: 0000000000000000 R09: 0000000000000000 [ 203.781839] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 203.781842] R13: ffff8ac10662c000 R14: ffff8ac0c004d400 R15: ffff8ac10662c008 [ 203.781846] FS: 00007f4cd8a67740(0000) GS:ffff8ad798880000(0000) knlGS:0000000000000000 [ 203.781851] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 203.781855] CR2: 0000559766a74028 CR3: 00000001804c4000 CR4: 00000000001506f0 [ 203.781862] Call Trace: [ 203.781870] <TASK> [ 203.851949] trace_event_buffer_commit+0x1ea/0x250 [ 203.851967] trace_event_raw_event_sys_enter+0x83/0xe0 [ 203.851983] syscall_trace_enter.isra.0+0x182/0x1a0 [ 203.851990] do_syscall_64+0x3a/0xe0 [ 203.852075] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 203.852090] RIP: 0033:0x7f4cd870fa77 [ 203.982920] Code: 00 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 90 b8 89 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e9 43 0e 00 f7 d8 64 89 01 48 [ 203.982932] RSP: 002b:00007fff99717dd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000089 [ 203.982942] RAX: ffffffffffffffda RBX: 0000558ea1d7b6f0 RCX: 00007f4cd870fa77 [ 203.982948] RDX: 0000000000000000 RSI: 00007fff99717de0 RDI: 0000558ea1d7b6f0 [ 203.982957] RBP: 00007fff99717de0 R08: 00007fff997180e0 R09: 00007fff997180e0 [ 203.982962] R10: 00007fff997180e0 R11: 0000000000000246 R12: 00007fff99717f40 [ 204.049239] R13: 00007fff99718590 R14: 0000558e9f2127a8 R15: 00007fff997180b0 [ 204.049256] </TASK> For instance, it can be triggered by running these two commands in parallel: $ while true; do echo hist:key=id.syscall:val=hitcount > \ /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger; done $ stress-ng --sysinfo $(nproc) The warning indicates that the current ring_buffer_per_cpu is not in the committing state. It happens because the active ring_buffer_event doesn't actually come from the ring_buffer_per_cpu but is allocated from trace_buffered_event. The bug is in function trace_buffered_event_disable() where the following normally happens: * The code invokes disable_trace_buffered_event() via smp_call_function_many() and follows it by synchronize_rcu(). This increments the per-CPU variable trace_buffered_event_cnt on each target CPU and grants trace_buffered_event_disable() the exclusive access to the per-CPU variable trace_buffered_event. * Maintenance is performed on trace_buffered_event, all per-CPU event buffers get freed. * The code invokes enable_trace_buffered_event() via smp_call_function_many(). This decrements trace_buffered_event_cnt and releases the access to trace_buffered_event. A problem is that smp_call_function_many() runs a given function on all target CPUs except on the current one. The following can then occur: * Task X executing trace_buffered_event_disable() runs on CPU 0. * The control reaches synchronize_rcu() and the task gets rescheduled on another CPU 1. * The RCU synchronization finishes. At this point, trace_buffered_event_disable() has the exclusive access to all trace_buffered_event variables except trace_buffered_event[CPU0] because trace_buffered_event_cnt[CPU0] is never incremented and if the buffer is currently unused, remains set to 0. * A different task Y is scheduled on CPU 0 and hits a trace event. The code in trace_event_buffer_lock_reserve() sees that trace_buffered_event_cnt[CPU0] is set to 0 and decides the use the buffer provided by trace_buffered_event[CPU0]. * Task X continues its execution in trace_buffered_event_disable(). The code incorrectly frees the event buffer pointed by trace_buffered_event[CPU0] and resets the variable to NULL. * Task Y writes event data to the now freed buffer and later detects the created inconsistency. The issue is observable since commit dea499781a11 ("tracing: Fix warning in trace_buffered_event_disable()") which moved the call of trace_buffered_event_disable() in __ftrace_event_enable_disable() earlier, prior to invoking call->class->reg(.. TRACE_REG_UNREGISTER ..). The underlying problem in trace_buffered_event_disable() is however present since the original implementation in commit 0fc1b09ff1ff ("tracing: Use temp buffer when filtering events"). Fix the problem by replacing the two smp_call_function_many() calls with on_each_cpu_mask() which invokes a given callback on all CPUs. Link: https://lore.kernel.org/all/20231127151248.7232-2-petr.pavlu@suse.com/ Link: https://lkml.kernel.org/r/20231205161736.19663-2-petr.pavlu@suse.com Cc: stable(a)vger.kernel.org Fixes: 0fc1b09ff1ff ("tracing: Use temp buffer when filtering events") Fixes: dea499781a11 ("tracing: Fix warning in trace_buffered_event_disable()") Signed-off-by: Petr Pavlu <petr.pavlu(a)suse.com> Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> --- kernel/trace/trace.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 2492c6c76850..6aeffa4a6994 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2781,11 +2781,9 @@ void trace_buffered_event_disable(void) if (--trace_buffered_event_ref) return; - preempt_disable(); /* For each CPU, set the buffer as used. */ - smp_call_function_many(tracing_buffer_mask, - disable_trace_buffered_event, NULL, 1); - preempt_enable(); + on_each_cpu_mask(tracing_buffer_mask, disable_trace_buffered_event, + NULL, true); /* Wait for all current users to finish */ synchronize_rcu(); @@ -2800,11 +2798,9 @@ void trace_buffered_event_disable(void) */ smp_wmb(); - preempt_disable(); /* Do the work on each cpu */ - smp_call_function_many(tracing_buffer_mask, - enable_trace_buffered_event, NULL, 1); - preempt_enable(); + on_each_cpu_mask(tracing_buffer_mask, enable_trace_buffered_event, NULL, + true); } static struct trace_buffer *temp_buffer; -- 2.42.0

1 year, 6 months

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[for-linus][PATCH 3/8] tracing: Disable snapshot buffer when stopping instance tracers

by Steven Rostedt

From: "Steven Rostedt (Google)" <rostedt(a)goodmis.org> It use to be that only the top level instance had a snapshot buffer (for latency tracers like wakeup and irqsoff). When stopping a tracer in an instance would not disable the snapshot buffer. This could have some unintended consequences if the irqsoff tracer is enabled. Consolidate the tracing_start/stop() with tracing_start/stop_tr() so that all instances behave the same. The tracing_start/stop() functions will just call their respective tracing_start/stop_tr() with the global_array passed in. Link: https://lkml.kernel.org/r/20231205220011.041220035@goodmis.org Cc: stable(a)vger.kernel.org Cc: Masami Hiramatsu <mhiramat(a)kernel.org> Cc: Mark Rutland <mark.rutland(a)arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com> Cc: Andrew Morton <akpm(a)linux-foundation.org> Fixes: 6d9b3fa5e7f6 ("tracing: Move tracing_max_latency into trace_array") Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> --- kernel/trace/trace.c | 110 +++++++++++++------------------------------ 1 file changed, 34 insertions(+), 76 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index e978868b1a22..2492c6c76850 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2360,13 +2360,7 @@ int is_tracing_stopped(void) return global_trace.stop_count; } -/** - * tracing_start - quick start of the tracer - * - * If tracing is enabled but was stopped by tracing_stop, - * this will start the tracer back up. - */ -void tracing_start(void) +static void tracing_start_tr(struct trace_array *tr) { struct trace_buffer *buffer; unsigned long flags; @@ -2374,119 +2368,83 @@ void tracing_start(void) if (tracing_disabled) return; - raw_spin_lock_irqsave(&global_trace.start_lock, flags); - if (--global_trace.stop_count) { - if (global_trace.stop_count < 0) { + raw_spin_lock_irqsave(&tr->start_lock, flags); + if (--tr->stop_count) { + if (WARN_ON_ONCE(tr->stop_count < 0)) { /* Someone screwed up their debugging */ - WARN_ON_ONCE(1); - global_trace.stop_count = 0; + tr->stop_count = 0; } goto out; } /* Prevent the buffers from switching */ - arch_spin_lock(&global_trace.max_lock); + arch_spin_lock(&tr->max_lock); - buffer = global_trace.array_buffer.buffer; + buffer = tr->array_buffer.buffer; if (buffer) ring_buffer_record_enable(buffer); #ifdef CONFIG_TRACER_MAX_TRACE - buffer = global_trace.max_buffer.buffer; + buffer = tr->max_buffer.buffer; if (buffer) ring_buffer_record_enable(buffer); #endif - arch_spin_unlock(&global_trace.max_lock); - - out: - raw_spin_unlock_irqrestore(&global_trace.start_lock, flags); -} - -static void tracing_start_tr(struct trace_array *tr) -{ - struct trace_buffer *buffer; - unsigned long flags; - - if (tracing_disabled) - return; - - /* If global, we need to also start the max tracer */ - if (tr->flags & TRACE_ARRAY_FL_GLOBAL) - return tracing_start(); - - raw_spin_lock_irqsave(&tr->start_lock, flags); - - if (--tr->stop_count) { - if (tr->stop_count < 0) { - /* Someone screwed up their debugging */ - WARN_ON_ONCE(1); - tr->stop_count = 0; - } - goto out; - } - - buffer = tr->array_buffer.buffer; - if (buffer) - ring_buffer_record_enable(buffer); + arch_spin_unlock(&tr->max_lock); out: raw_spin_unlock_irqrestore(&tr->start_lock, flags); } /** - * tracing_stop - quick stop of the tracer + * tracing_start - quick start of the tracer * - * Light weight way to stop tracing. Use in conjunction with - * tracing_start. + * If tracing is enabled but was stopped by tracing_stop, + * this will start the tracer back up. */ -void tracing_stop(void) +void tracing_start(void) + +{ + return tracing_start_tr(&global_trace); +} + +static void tracing_stop_tr(struct trace_array *tr) { struct trace_buffer *buffer; unsigned long flags; - raw_spin_lock_irqsave(&global_trace.start_lock, flags); - if (global_trace.stop_count++) + raw_spin_lock_irqsave(&tr->start_lock, flags); + if (tr->stop_count++) goto out; /* Prevent the buffers from switching */ - arch_spin_lock(&global_trace.max_lock); + arch_spin_lock(&tr->max_lock); - buffer = global_trace.array_buffer.buffer; + buffer = tr->array_buffer.buffer; if (buffer) ring_buffer_record_disable(buffer); #ifdef CONFIG_TRACER_MAX_TRACE - buffer = global_trace.max_buffer.buffer; + buffer = tr->max_buffer.buffer; if (buffer) ring_buffer_record_disable(buffer); #endif - arch_spin_unlock(&global_trace.max_lock); + arch_spin_unlock(&tr->max_lock); out: - raw_spin_unlock_irqrestore(&global_trace.start_lock, flags); + raw_spin_unlock_irqrestore(&tr->start_lock, flags); } -static void tracing_stop_tr(struct trace_array *tr) +/** + * tracing_stop - quick stop of the tracer + * + * Light weight way to stop tracing. Use in conjunction with + * tracing_start. + */ +void tracing_stop(void) { - struct trace_buffer *buffer; - unsigned long flags; - - /* If global, we need to also stop the max tracer */ - if (tr->flags & TRACE_ARRAY_FL_GLOBAL) - return tracing_stop(); - - raw_spin_lock_irqsave(&tr->start_lock, flags); - if (tr->stop_count++) - goto out; - - buffer = tr->array_buffer.buffer; - if (buffer) - ring_buffer_record_disable(buffer); - - out: - raw_spin_unlock_irqrestore(&tr->start_lock, flags); + return tracing_stop_tr(&global_trace); } static int trace_save_cmdline(struct task_struct *tsk) -- 2.42.0

1 year, 6 months

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[for-linus][PATCH 2/8] tracing: Stop current tracer when resizing buffer

by Steven Rostedt

From: "Steven Rostedt (Google)" <rostedt(a)goodmis.org> When the ring buffer is being resized, it can cause side effects to the running tracer. For instance, there's a race with irqsoff tracer that swaps individual per cpu buffers between the main buffer and the snapshot buffer. The resize operation modifies the main buffer and then the snapshot buffer. If a swap happens in between those two operations it will break the tracer. Simply stop the running tracer before resizing the buffers and enable it again when finished. Link: https://lkml.kernel.org/r/20231205220010.748996423@goodmis.org Cc: stable(a)vger.kernel.org Cc: Masami Hiramatsu <mhiramat(a)kernel.org> Cc: Mark Rutland <mark.rutland(a)arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com> Cc: Andrew Morton <akpm(a)linux-foundation.org> Fixes: 3928a8a2d9808 ("ftrace: make work with new ring buffer") Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> --- kernel/trace/trace.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 231c173ec04f..e978868b1a22 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6387,9 +6387,12 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr, if (!tr->array_buffer.buffer) return 0; + /* Do not allow tracing while resizng ring buffer */ + tracing_stop_tr(tr); + ret = ring_buffer_resize(tr->array_buffer.buffer, size, cpu); if (ret < 0) - return ret; + goto out_start; #ifdef CONFIG_TRACER_MAX_TRACE if (!tr->current_trace->use_max_tr) @@ -6417,7 +6420,7 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr, WARN_ON(1); tracing_disabled = 1; } - return ret; + goto out_start; } update_buffer_entries(&tr->max_buffer, cpu); @@ -6426,7 +6429,8 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr, #endif /* CONFIG_TRACER_MAX_TRACE */ update_buffer_entries(&tr->array_buffer, cpu); - + out_start: + tracing_start_tr(tr); return ret; } -- 2.42.0

1 year, 6 months

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[for-linus][PATCH 1/8] tracing: Always update snapshot buffer size

by Steven Rostedt

From: "Steven Rostedt (Google)" <rostedt(a)goodmis.org> It use to be that only the top level instance had a snapshot buffer (for latency tracers like wakeup and irqsoff). The update of the ring buffer size would check if the instance was the top level and if so, it would also update the snapshot buffer as it needs to be the same as the main buffer. Now that lower level instances also has a snapshot buffer, they too need to update their snapshot buffer sizes when the main buffer is changed, otherwise the following can be triggered: # cd /sys/kernel/tracing # echo 1500 > buffer_size_kb # mkdir instances/foo # echo irqsoff > instances/foo/current_tracer # echo 1000 > instances/foo/buffer_size_kb Produces: WARNING: CPU: 2 PID: 856 at kernel/trace/trace.c:1938 update_max_tr_single.part.0+0x27d/0x320 Which is: ret = ring_buffer_swap_cpu(tr->max_buffer.buffer, tr->array_buffer.buffer, cpu); if (ret == -EBUSY) { [..] } WARN_ON_ONCE(ret && ret != -EAGAIN && ret != -EBUSY); <== here That's because ring_buffer_swap_cpu() has: int ret = -EINVAL; [..] /* At least make sure the two buffers are somewhat the same */ if (cpu_buffer_a->nr_pages != cpu_buffer_b->nr_pages) goto out; [..] out: return ret; } Instead, update all instances' snapshot buffer sizes when their main buffer size is updated. Link: https://lkml.kernel.org/r/20231205220010.454662151@goodmis.org Cc: stable(a)vger.kernel.org Cc: Masami Hiramatsu <mhiramat(a)kernel.org> Cc: Mark Rutland <mark.rutland(a)arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com> Cc: Andrew Morton <akpm(a)linux-foundation.org> Fixes: 6d9b3fa5e7f6 ("tracing: Move tracing_max_latency into trace_array") Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> --- kernel/trace/trace.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 9aebf904ff97..231c173ec04f 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6392,8 +6392,7 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr, return ret; #ifdef CONFIG_TRACER_MAX_TRACE - if (!(tr->flags & TRACE_ARRAY_FL_GLOBAL) || - !tr->current_trace->use_max_tr) + if (!tr->current_trace->use_max_tr) goto out; ret = ring_buffer_resize(tr->max_buffer.buffer, size, cpu); -- 2.42.0

1 year, 6 months

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patch "serial: ma35d1: Validate console index before assignment" added to tty-linus

by gregkh＠linuxfoundation.org

This is a note to let you know that I've just added the patch titled serial: ma35d1: Validate console index before assignment to my tty git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git in the tty-linus branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will hopefully also be merged in Linus's tree for the next -rc kernel release. If you have any questions about this process, please let me know. From f0b9d97a77fa8f18400450713358303a435ab688 Mon Sep 17 00:00:00 2001 From: Andi Shyti <andi.shyti(a)kernel.org> Date: Mon, 4 Dec 2023 17:38:03 +0100 Subject: serial: ma35d1: Validate console index before assignment The console is immediately assigned to the ma35d1 port without checking its index. This oversight can lead to out-of-bounds errors when the index falls outside the valid '0' to MA35_UART_NR range. Such scenario trigges ran error like the following: UBSAN: array-index-out-of-bounds in drivers/tty/serial/ma35d1_serial.c:555:51 index -1 is out of range for type 'uart_ma35d1_port [17] Check the index before using it and bail out with a warning. Fixes: 930cbf92db01 ("tty: serial: Add Nuvoton ma35d1 serial driver support") Signed-off-by: Andi Shyti <andi.shyti(a)kernel.org> Cc: Jacky Huang <ychuang3(a)nuvoton.com> Cc: <stable(a)vger.kernel.org> # v6.5+ Link: https://lore.kernel.org/r/20231204163804.1331415-2-andi.shyti@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/tty/serial/ma35d1_serial.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/ma35d1_serial.c b/drivers/tty/serial/ma35d1_serial.c index a6a7c405892e..21b574f78b86 100644 --- a/drivers/tty/serial/ma35d1_serial.c +++ b/drivers/tty/serial/ma35d1_serial.c @@ -552,11 +552,19 @@ static void ma35d1serial_console_putchar(struct uart_port *port, unsigned char c */ static void ma35d1serial_console_write(struct console *co, const char *s, u32 count) { - struct uart_ma35d1_port *up = &ma35d1serial_ports[co->index]; + struct uart_ma35d1_port *up; unsigned long flags; int locked = 1; u32 ier; + if ((co->index < 0) || (co->index >= MA35_UART_NR)) { + pr_warn("Failed to write on ononsole port %x, out of range\n", + co->index); + return; + } + + up = &ma35d1serial_ports[co->index]; + if (up->port.sysrq) locked = 0; else if (oops_in_progress) -- 2.43.0

1 year, 6 months

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[PATCH] irq: Resolve that mask_irq/unmask_irq may not be called in pairs

by xiongxin

When an interrupt controller uses a function such as handle_level_irq() as an interrupt handler and the controller implements the irq_disable() callback, the following scenario will appear in the i2c-hid driver in the sleep scenario: in the sleep flow, while the user is still triggering the i2c-hid interrupt, we get the following function call: handle_level_irq() -> mask_ack_irq() -> mask_irq() i2c_hid_core_suspend() -> disable_irq() -> __irq_disable() -> irq_state_set_disabled() -> irq_state_set_masked() irq_thread_fn() -> irq_finalize_oneshot() -> if (!desc->threads_oneshot && !irqd_irq_disabled() && irqd_irq_masked()) unmask_threaded_irq() -> unmask_irq() That is, when __irq_disable() is called between mask_irq() and irq_finalize_oneshot(), the code in irq_finalize_oneshot() will cause the !irqd_irq_disabled() fails to enter the unmask_irq() branch, which causes mask_irq/unmask_irq to be called unpaired and the i2c-hid interrupt to be masked. Since mask_irq/unmask_irq and irq_disabled() belong to two different hardware registers or policies, the !irqd_irq_disabled() assertion may not be used to determine whether unmask_irq() needs to be called. Cc: stable(a)vger.kernel.org Signed-off-by: xiongxin <xiongxin(a)kylinos.cn> Signed-off-by: Riwen Lu <luriwen(a)kylinos.cn> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 1782f90cd8c6..9160fc9170b3 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -1120,8 +1120,7 @@ static void irq_finalize_oneshot(struct irq_desc *desc, desc->threads_oneshot &= ~action->thread_mask; - if (!desc->threads_oneshot && !irqd_irq_disabled(&desc->irq_data) && - irqd_irq_masked(&desc->irq_data)) + if (!desc->threads_oneshot && irqd_irq_masked(&desc->irq_data)) unmask_threaded_irq(desc); out_unlock: -- 2.34.1

1 year, 6 months

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Re: [PATCH] team: Fix use-after-free when an option instance allocation fails

by Florent Revest

On Wed, Dec 6, 2023 at 4:05 PM Hangbin Liu <liuhangbin(a)gmail.com> wrote: > > On Wed, Dec 06, 2023 at 01:37:18PM +0100, Florent Revest wrote: > > In __team_options_register, team_options are allocated and appended to > > the team's option_list. > > If one option instance allocation fails, the "inst_rollback" cleanup > > path frees the previously allocated options but doesn't remove them from > > the team's option_list. > > This leaves dangling pointers that can be dereferenced later by other > > parts of the team driver that iterate over options. > > > > This patch fixes the cleanup path to remove the dangling pointers from > > the list. > > > > As far as I can tell, this uaf doesn't have much security implications > > since it would be fairly hard to exploit (an attacker would need to make > > the allocation of that specific small object fail) but it's still nice > > to fix. > > > > Fixes: 80f7c6683fe0 ("team: add support for per-port options") > > Signed-off-by: Florent Revest <revest(a)chromium.org> > > Reviewed-by: Hangbin Liu <liuhangbin(a)gmail.com> Thank you for the quick reviews Hangbin & Jiri, I appreciate! :) I just realized I forgot to CC stable (like I always do... :) maybe I should tattoo it on my arm) Let me know if you'd like a v2 adding: Cc: stable(a)vger.kernel.org

1 year, 6 months

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Linux-stable-mirror December 2023