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The number of pages for those ring buffers must fit into that variable. Enforce this limit on ring buffer creation or user-mapping. While at it, make buffer_page::id 31 bits. This does not change the struct buffer_page size. Fixes: be68d63a139b ("ring-buffer: Add ring_buffer_alloc_range()") Signed-off-by: Vincent Donnefort diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index ec13779922ff..5e26eeff588f 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -345,7 +345,7 @@ struct buffer_page { local_t entries; /* entries on this page */ unsigned long real_end; /* real end of data */ unsigned order; /* order of the page */ - u32 id:30; /* ID for external mapping */ + u32 id:31; /* ID for external mapping */ u32 range:1; /* Mapped via a range */ struct buffer_data_page *page; /* Actual data page */ }; @@ -652,6 +652,15 @@ static bool rb_is_static(struct ring_buffer_per_cpu *cpu_buffer) return cpu_buffer->user_mapped || cpu_buffer->remote || cpu_buffer->ring_meta; } +static unsigned long rb_static_max_pages(void) +{ + /* + * Static ring buffers are using bpage::id and must account for the + * reader page. + */ + return (1UL << 31) - 1; +} + struct ring_buffer_iter { struct ring_buffer_per_cpu *cpu_buffer; unsigned long head; @@ -2837,6 +2846,10 @@ static struct trace_buffer *alloc_buffer(unsigned long size, unsigned flags, */ nr_pages = (size - sizeof(struct ring_buffer_cpu_meta)) / (subbuf_size + sizeof(int)); + + if (nr_pages > rb_static_max_pages()) + goto fail_free_buffers; + /* Need at least two pages plus the reader page */ if (nr_pages < 3) goto fail_free_buffers; @@ -2869,6 +2882,10 @@ static struct trace_buffer *alloc_buffer(unsigned long size, unsigned flags, /* The writer is remote. This ring-buffer is read-only */ atomic_inc(&buffer->record_disabled); nr_pages = desc->nr_page_va - 1; + + if (nr_pages > rb_static_max_pages()) + goto fail_free_buffers; + if (nr_pages < 2) goto fail_free_buffers; } else { @@ -7834,6 +7851,9 @@ int ring_buffer_map(struct trace_buffer *buffer, int cpu, /* prevent another thread from changing buffer/sub-buffer sizes */ guard(mutex)(&buffer->mutex); + if (cpu_buffer->nr_pages > rb_static_max_pages()) + return -E2BIG; + err = rb_alloc_meta_page(cpu_buffer); if (err) return err; -- 2.55.0.691.gc56d675ccc-goog