From nobody Mon Sep 28 23:55:28 2026 Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1C5934734E5 for ; Fri, 14 Aug 2026 15:48:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.71 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786722511; cv=none; b=ANwsrKNUqEh06gxh/Ng6+oQz9ynOu2VGyuE1auUM3db3TQq6SVvUL/s11ZtXle3gljOFSe3Ypy+dXX/3xtfR3LxH2UPBf7FbbC0QvqcJvFa753Bu3UxVM03AOpeOeBqxAEvLLT2Letc7L6cO10rzvjuqB5P09E8UeVaJ0oqCwq0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786722511; c=relaxed/simple; bh=vCINmSJb9yZg5xEVHdEsLNU9vN/Gy2+jMIw4/AOwC7Y=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=pvNA/wGtvw81OiyDAzmcxHQTYcWeSYvfVDLcRBiirApeQfcpgt/5+ckZlwRlrZFlcf8v+AhqJvYZFqFJ6xNoYvmomXK9axIQIWU9y+mr7pHO5YTfkW3Xa9Gow4S3pnNUI6Hp+KQ79rmmWDHMo6wiQOB+lELY0WPWe2N3Ws0XjYA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=FkrKBKEL; arc=none smtp.client-ip=209.85.128.71 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="FkrKBKEL" Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-4994aebe932so12040735e9.3 for ; Fri, 14 Aug 2026 08:48:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1786722507; x=1787327307; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=nV1pWWkD5bsCCpYwQOvn4bitJK+uOOJiLtYFD+r/bCQ=; b=FkrKBKELyfgs4S+8mXzFKDh5QaefPjH64UYRohTDwMrmoX4yPzQIY42f48h4bqDelk 1T8Rmv3sNQ0C8we7u34PyeHhQqfKG3tNAOYuWE5Cxh9yl0N3cIBFVIbhIV/Ce24Z/1tZ EZ7Z4WPsjfSxMCsgAFZV9jsThWoahEskaUilcKLo7M09+Lh4cyhjn/2YPMJbFWa2df7M CwkKqqtIVV8Z1UWCk1MOplQ6dmW1xBIMr5oOWtYPlB0tqnNfKs7uHFEaykjsAR59Gaax UdLVYT6oSVqUzxkkVAYLJ6PeXNfTA000vvqGi77/hQEbnTQDgBiSJSunjgiX0UyKyvYK SWNw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1786722507; x=1787327307; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=nV1pWWkD5bsCCpYwQOvn4bitJK+uOOJiLtYFD+r/bCQ=; b=M7dmagLyafJIUMpqIMR4IfFvYMWXKm0Z2Fg1hdw9i4qFS6V4y/RdQOxZqCd5sFejVt eDonFX5T7MeLtvJvsvaKsKJg3NGvcwQSyffJWNZmE/pYXEK6+YEVqZacYksGhFAYKXzU /rtW5nfr95xpQj6N7h//w3+06uEym4q4m8A0PK2CEaCZuucGs1Dhn8151/nb2YN8zNV7 KGQsYblOnwwGPHsmIfqW41wEMGDBdt5bsC4/PnUkuhYuYqddTHzB4sQisAVaitaAozNs lsq5I383bwgyEX+AXerZ19Zv2blfqZ5OqB4tjNbLD/4y9oGYCfodiTYdXiiW03B/Z/Q4 X0Sw== X-Forwarded-Encrypted: i=1; AHgh+RpysgK6CL6KQKonHujBI+ErVJ/VrHnqacjv6GU5wVKPP/dWUmlgsfGHyauklHVXz5wtlr1ICCR9Mipl6y0=@vger.kernel.org X-Gm-Message-State: AOJu0YxM4sOTbrar8MAaD/1e4jC7EvT+YDr0uMcxPLjBJ9AUJvagVXsd Mo4hbkrgivhqG+8uQOlGKmUKCGJFZ1Upt2DH2fsDVN6NfIc6HgojdVq1D1WTbPUBK8jMUk2MTBR FdTFLpbBDwt+V+xIOCuNU2Q== X-Received: from wmti12.prod.google.com ([2002:a05:600c:8b8c:b0:495:5762:2123]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:1385:b0:499:5220:db3d with SMTP id 5b1f17b1804b1-499879a50afmr75294865e9.16.1786722507053; Fri, 14 Aug 2026 08:48:27 -0700 (PDT) Date: Fri, 14 Aug 2026 16:48:22 +0100 In-Reply-To: <20260814154823.755406-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260814154823.755406-1-vdonnefort@google.com> X-Mailer: git-send-email 2.55.0.691.gc56d675ccc-goog Message-ID: <20260814154823.755406-2-vdonnefort@google.com> Subject: [PATCH v6 1/2] tracing: Fix subbuf resize races with trace_pipe_raw readers From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, linux-trace-kernel@vger.kernel.org Cc: mathieu.desnoyers@efficios.com, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Concurrent subbuffer resizes may crash trace_pipe_raw readers or leak uninitialized memory to userspace due to stale size values. Modify ring_buffer_alloc_read_page() to let it handle the resizing of a previous buffer_data_read_page if necessary and add a new ring_buffer_read_page_size() which enable ring-buffer users to not use the racy ring_buffer_subbuf_size_get(). This makes the spare_size member of ftrace_buffer_info redundant. Use those functions in trace_pipe_raw readers and handle in both the case where the subbuf order is modified in the middle of the read. Fixes: bce761d75745 ("ring-buffer: Read and write to ring buffers with cust= om sub buffer size") Signed-off-by: Vincent Donnefort --- include/linux/ring_buffer.h | 5 +- kernel/trace/ring_buffer.c | 100 ++++++++++++++++++-------- kernel/trace/ring_buffer_benchmark.c | 6 +- kernel/trace/trace.c | 104 +++++++++++++-------------- kernel/trace/trace.h | 9 ++- 5 files changed, 130 insertions(+), 94 deletions(-) diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index 0670742b2d60..afc7daa6ee7d 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -218,14 +218,15 @@ bool ring_buffer_time_stamp_abs(struct trace_buffer *= buffer); size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu); =20 struct buffer_data_read_page; -struct buffer_data_read_page * -ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu); +int ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu, + struct buffer_data_read_page **rpage); void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, struct buffer_data_read_page *page); int ring_buffer_read_page(struct trace_buffer *buffer, struct buffer_data_read_page *data_page, size_t len, int cpu, int full); void *ring_buffer_read_page_data(struct buffer_data_read_page *page); +unsigned int ring_buffer_read_page_size(struct buffer_data_read_page *rpag= e); =20 struct trace_seq; =20 diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 5fc009edc1ec..ec13779922ff 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -6990,56 +6990,78 @@ EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); * ring_buffer_alloc_read_page - allocate a page to read from buffer * @buffer: the buffer to allocate for. * @cpu: the cpu buffer to allocate. + * @rpage: pointer to pass in an already allocated page (can be NULL) + * and returns the allocated page. * - * This function is used in conjunction with ring_buffer_read_page. + * This function is used in conjunction with ring_buffer_read_page(). * When reading a full page from the ring buffer, these functions * can be used to speed up the process. The calling function should * allocate a few pages first with this function. Then when it * needs to get pages from the ring buffer, it passes the result - * of this function into ring_buffer_read_page, which will swap + * of this function into ring_buffer_read_page(), which will swap * the page that was allocated, with the read page of the buffer. * + * If @rpage is provided, and it has a different order than the current + * subbuffer order, its payload will be freed and re-allocated. If it + * already matches the order, it is simply returned. + * * Returns: - * The page allocated, or ERR_PTR + * 0 on success, < 0 on error */ -struct buffer_data_read_page * -ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu) +int ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu, + struct buffer_data_read_page **rpage) { struct ring_buffer_per_cpu *cpu_buffer; - struct buffer_data_read_page *bpage =3D NULL; unsigned long flags; + unsigned int order; =20 if (!cpumask_test_cpu(cpu, buffer->cpumask)) - return ERR_PTR(-ENODEV); + return -ENODEV; =20 - bpage =3D kzalloc_obj(*bpage); - if (!bpage) - return ERR_PTR(-ENOMEM); + if (!rpage) + return -EINVAL; =20 - bpage->order =3D buffer->subbuf_order; + order =3D buffer->subbuf_order; + + if (*rpage) { + if ((*rpage)->order =3D=3D order) + return 0; + + /* We can reuse rpage, but we discard the payload */ + free_pages((unsigned long)(*rpage)->data, (*rpage)->order); + (*rpage)->data =3D NULL; + } else { + *rpage =3D kzalloc_obj(**rpage); + if (!*rpage) + return -ENOMEM; + } + + (*rpage)->order =3D order; cpu_buffer =3D buffer->buffers[cpu]; + local_irq_save(flags); arch_spin_lock(&cpu_buffer->lock); =20 if (cpu_buffer->free_page.data) { - *bpage =3D cpu_buffer->free_page; + **rpage =3D cpu_buffer->free_page; cpu_buffer->free_page.data =3D NULL; } =20 arch_spin_unlock(&cpu_buffer->lock); local_irq_restore(flags); =20 - if (bpage->data) { - rb_init_data_page(bpage->data); + if ((*rpage)->data) { + rb_init_data_page((*rpage)->data); } else { - bpage->data =3D alloc_cpu_data(cpu, bpage->order); - if (!bpage->data) { - kfree(bpage); - return ERR_PTR(-ENOMEM); + (*rpage)->data =3D alloc_cpu_data(cpu, (*rpage)->order); + if (!(*rpage)->data) { + kfree(*rpage); + *rpage =3D NULL; + return -ENOMEM; } } =20 - return bpage; + return 0; } EXPORT_SYMBOL_GPL(ring_buffer_alloc_read_page); =20 @@ -7047,21 +7069,30 @@ EXPORT_SYMBOL_GPL(ring_buffer_alloc_read_page); * ring_buffer_free_read_page - free an allocated read page * @buffer: the buffer the page was allocate for * @cpu: the cpu buffer the page came from - * @data_page: the page to free + * @rpage: the buffer_dat_read_page to free * * Free a page allocated from ring_buffer_alloc_read_page. */ void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, - struct buffer_data_read_page *data_page) + struct buffer_data_read_page *rpage) { struct ring_buffer_per_cpu *cpu_buffer; - struct buffer_data_page *dpage =3D data_page->data; - struct page *page =3D virt_to_page(dpage); + struct buffer_data_page *dpage; unsigned long flags; + struct page *page; =20 if (!buffer || !buffer->buffers || !buffer->buffers[cpu]) return; =20 + if (!rpage) + return; + + dpage =3D rpage->data; + if (!dpage) + goto out; + + page =3D virt_to_page(dpage); + cpu_buffer =3D buffer->buffers[cpu]; =20 /* @@ -7069,14 +7100,14 @@ void ring_buffer_free_read_page(struct trace_buffer= *buffer, int cpu, * is different from the subbuffer order of the buffer - * we can't reuse it */ - if (page_ref_count(page) > 1 || data_page->order !=3D buffer->subbuf_orde= r) + if (page_ref_count(page) > 1 || rpage->order !=3D buffer->subbuf_order) goto out; =20 local_irq_save(flags); arch_spin_lock(&cpu_buffer->lock); =20 if (!cpu_buffer->free_page.data) { - cpu_buffer->free_page =3D *data_page; + cpu_buffer->free_page =3D *rpage; dpage =3D NULL; } =20 @@ -7084,8 +7115,8 @@ void ring_buffer_free_read_page(struct trace_buffer *= buffer, int cpu, local_irq_restore(flags); =20 out: - free_pages((unsigned long)dpage, data_page->order); - kfree(data_page); + free_pages((unsigned long)dpage, rpage->order); + kfree(rpage); } EXPORT_SYMBOL_GPL(ring_buffer_free_read_page); =20 @@ -7122,6 +7153,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_free_read_page); * Returns: * >=3D0 if data has been transferred, returns the offset of consumed dat= a. * <0 if no data has been transferred. + * -EAGAIN if the subbuf size has changed and @data_page must be realloca= ted. */ int ring_buffer_read_page(struct trace_buffer *buffer, struct buffer_data_read_page *data_page, @@ -7159,7 +7191,7 @@ int ring_buffer_read_page(struct trace_buffer *buffer, guard(raw_spinlock_irqsave)(&cpu_buffer->reader_lock); =20 if (data_page->order !=3D cpu_buffer->reader_page->order) - return -1; + return -EAGAIN; =20 reader =3D rb_get_reader_page(cpu_buffer); if (!reader) @@ -7323,6 +7355,18 @@ void *ring_buffer_read_page_data(struct buffer_data_= read_page *page) } EXPORT_SYMBOL_GPL(ring_buffer_read_page_data); =20 +/** + * ring_buffer_read_page_size - get size of the read page. + * @page: the page to get the size from + * + * Returns size of the page in bytes. + */ +unsigned int ring_buffer_read_page_size(struct buffer_data_read_page *rpag= e) +{ + return PAGE_SIZE << rpage->order; +} +EXPORT_SYMBOL_GPL(ring_buffer_read_page_size); + /** * ring_buffer_subbuf_size_get - get size of the sub buffer. * @buffer: the buffer to get the sub buffer size from diff --git a/kernel/trace/ring_buffer_benchmark.c b/kernel/trace/ring_buffe= r_benchmark.c index 593e3b59e42e..c3d34c0e64e2 100644 --- a/kernel/trace/ring_buffer_benchmark.c +++ b/kernel/trace/ring_buffer_benchmark.c @@ -104,7 +104,7 @@ static enum event_status read_event(int cpu) =20 static enum event_status read_page(int cpu) { - struct buffer_data_read_page *bpage; + struct buffer_data_read_page *bpage =3D NULL; struct ring_buffer_event *event; struct rb_page *rpage; unsigned long commit; @@ -114,8 +114,8 @@ static enum event_status read_page(int cpu) int inc; int i; =20 - bpage =3D ring_buffer_alloc_read_page(buffer, cpu); - if (IS_ERR(bpage)) + ret =3D ring_buffer_alloc_read_page(buffer, cpu, &bpage); + if (ret < 0) return EVENT_DROPPED; =20 page_size =3D ring_buffer_subbuf_size_get(buffer); diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 395238b2b715..355278083b3f 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -7080,8 +7080,8 @@ ssize_t tracing_buffers_read(struct file *filp, char = __user *ubuf, { struct ftrace_buffer_info *info =3D filp->private_data; struct trace_iterator *iter =3D &info->iter; + unsigned int spare_size; void *trace_data; - int page_size; ssize_t ret =3D 0; ssize_t size; =20 @@ -7091,36 +7091,21 @@ ssize_t tracing_buffers_read(struct file *filp, cha= r __user *ubuf, if (iter->snapshot && tracer_uses_snapshot(iter->tr->current_trace)) return -EBUSY; =20 - page_size =3D ring_buffer_subbuf_size_get(iter->array_buffer->buffer); - - /* Make sure the spare matches the current sub buffer size */ - if (info->spare) { - if (page_size !=3D info->spare_size) { - ring_buffer_free_read_page(iter->array_buffer->buffer, - info->spare_cpu, info->spare); - info->spare =3D NULL; - } - } - - if (!info->spare) { - info->spare =3D ring_buffer_alloc_read_page(iter->array_buffer->buffer, - iter->cpu_file); - if (IS_ERR(info->spare)) { - ret =3D PTR_ERR(info->spare); - info->spare =3D NULL; - } else { - info->spare_cpu =3D iter->cpu_file; - info->spare_size =3D page_size; - } - } - if (!info->spare) - return ret; - +again: /* Do we have previous read data to read? */ - if (info->read < page_size) + if (info->spare && (info->read < ring_buffer_read_page_size(info->spare))) goto read; =20 - again: + /* Make sure the read page order is aligned with the current buffer subbu= f order */ + ret =3D ring_buffer_alloc_read_page(iter->array_buffer->buffer, iter->cpu= _file, + &info->spare); + if (ret < 0) + return ret; + + spare_size =3D ring_buffer_read_page_size(info->spare); + info->read =3D spare_size; + info->spare_cpu =3D iter->cpu_file; + trace_access_lock(iter->cpu_file); ret =3D ring_buffer_read_page(iter->array_buffer->buffer, info->spare, @@ -7128,7 +7113,9 @@ ssize_t tracing_buffers_read(struct file *filp, char = __user *ubuf, iter->cpu_file, 0); trace_access_unlock(iter->cpu_file); =20 - if (ret < 0) { + if (ret =3D=3D -EAGAIN) { + goto again; + } else if (ret < 0) { if (trace_empty(iter) && !iter->closed) { if (update_last_data_if_empty(iter->tr)) return 0; @@ -7146,8 +7133,9 @@ ssize_t tracing_buffers_read(struct file *filp, char = __user *ubuf, } =20 info->read =3D 0; + read: - size =3D page_size - info->read; + size =3D spare_size - info->read; if (size > count) size =3D count; trace_data =3D ring_buffer_read_page_data(info->spare); @@ -7197,17 +7185,17 @@ int tracing_buffers_release(struct inode *inode, st= ruct file *file) } =20 struct buffer_ref { - struct trace_buffer *buffer; - void *page; - int cpu; - refcount_t refcount; + struct trace_buffer *buffer; + struct buffer_data_read_page *rpage; + int cpu; + refcount_t refcount; }; =20 static void buffer_ref_release(struct buffer_ref *ref) { if (!refcount_dec_and_test(&ref->refcount)) return; - ring_buffer_free_read_page(ref->buffer, ref->cpu, ref->page); + ring_buffer_free_read_page(ref->buffer, ref->cpu, ref->rpage); kfree(ref); } =20 @@ -7268,23 +7256,12 @@ ssize_t tracing_buffers_splice_read(struct file *fi= le, loff_t *ppos, }; struct buffer_ref *ref; bool woken =3D false; - int page_size; int entries, i; ssize_t ret =3D 0; =20 if (iter->snapshot && tracer_uses_snapshot(iter->tr->current_trace)) return -EBUSY; =20 - page_size =3D ring_buffer_subbuf_size_get(iter->array_buffer->buffer); - if (*ppos & (page_size - 1)) - return -EINVAL; - - if (len & (page_size - 1)) { - if (len < page_size) - return -EINVAL; - len &=3D (~(page_size - 1)); - } - if (splice_grow_spd(pipe, &spd)) return -ENOMEM; =20 @@ -7292,7 +7269,8 @@ ssize_t tracing_buffers_splice_read(struct file *file= , loff_t *ppos, trace_access_lock(iter->cpu_file); entries =3D ring_buffer_entries_cpu(iter->array_buffer->buffer, iter->cpu= _file); =20 - for (i =3D 0; i < spd.nr_pages_max && len && entries; i++, len -=3D page_= size) { + for (i =3D 0; i < spd.nr_pages_max && len && entries; i++) { + unsigned int page_size; struct page *page; int r; =20 @@ -7304,25 +7282,38 @@ ssize_t tracing_buffers_splice_read(struct file *fi= le, loff_t *ppos, =20 refcount_set(&ref->refcount, 1); ref->buffer =3D iter->array_buffer->buffer; - ref->page =3D ring_buffer_alloc_read_page(ref->buffer, iter->cpu_file); - if (IS_ERR(ref->page)) { - ret =3D PTR_ERR(ref->page); - ref->page =3D NULL; + +new_read_page: + ret =3D ring_buffer_alloc_read_page(ref->buffer, iter->cpu_file, &ref->r= page); + if (ret < 0) { kfree(ref); break; } ref->cpu =3D iter->cpu_file; =20 - r =3D ring_buffer_read_page(ref->buffer, ref->page, - len, iter->cpu_file, 1); + page_size =3D ring_buffer_read_page_size(ref->rpage); + + r =3D -EINVAL; + if (IS_ALIGNED(*ppos, page_size) && len >=3D page_size) { + r =3D ring_buffer_read_page(ref->buffer, ref->rpage, len, iter->cpu_fil= e, 1); + if (r =3D=3D -EAGAIN) + goto new_read_page; + } else if (!i) { + /* + * If the first iteration fails this is an invalid userspace input. + * Otherwise, this is because the subbuf order has been modified. Do not + * report an error and finish the read. + */ + ret =3D -EINVAL; + } + if (r < 0) { - ring_buffer_free_read_page(ref->buffer, ref->cpu, - ref->page); + ring_buffer_free_read_page(ref->buffer, ref->cpu, ref->rpage); kfree(ref); break; } =20 - page =3D virt_to_page(ring_buffer_read_page_data(ref->page)); + page =3D virt_to_page(ring_buffer_read_page_data(ref->rpage)); =20 spd.pages[i] =3D page; spd.partial[i].len =3D page_size; @@ -7330,6 +7321,7 @@ ssize_t tracing_buffers_splice_read(struct file *file= , loff_t *ppos, spd.partial[i].private =3D (unsigned long)ref; spd.nr_pages++; *ppos +=3D page_size; + len -=3D page_size; =20 entries =3D ring_buffer_entries_cpu(iter->array_buffer->buffer, iter->cp= u_file); } diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index bf77331f56a4..cbf54eded447 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -745,11 +745,10 @@ static inline int tracing_get_cpu(struct inode *inode) void tracing_reset_cpu(struct array_buffer *buf, int cpu); 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charset="utf-8" If ring_buffer_per_cpu::nr_pages is defined as unsigned long, it is capped to 32-bits in a few places, limiting the operations possible on a very large buffer. Make sure nr_pages is never capped to 32-bits (that includes nr_subbufs) and reject a value over 32-bits for the user-mapped, persistent buffer and remote buffer cases where the limiting factor is the shared meta-data member for the number of pages/subbufs. While at it, make sure subbuf_size is 'unsigned int'. Signed-off-by: Vincent Donnefort --- kernel/trace/ring_buffer.c | 46 ++++++++++++++++++++++++-------------- 1 file changed, 29 insertions(+), 17 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index ec13779922ff..ec127e2ad052 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1669,7 +1669,7 @@ static void rb_check_pages(struct ring_buffer_per_cpu= *cpu_buffer) * This is used to help find the next per cpu subbuffer within a mapped ra= nge. */ static unsigned long -rb_range_align_subbuf(unsigned long addr, int subbuf_size, int nr_subbufs) +rb_range_align_subbuf(unsigned long addr, unsigned int subbuf_size, unsign= ed long nr_subbufs) { addr +=3D sizeof(struct ring_buffer_cpu_meta) + sizeof(int) * nr_subbufs; @@ -1679,13 +1679,12 @@ rb_range_align_subbuf(unsigned long addr, int subbu= f_size, int nr_subbufs) /* * Return the ring_buffer_meta for a given @cpu. */ -static void *rb_range_meta(struct trace_buffer *buffer, int nr_pages, int = cpu) +static void *rb_range_meta(struct trace_buffer *buffer, unsigned long nr_p= ages, int cpu) { - int subbuf_size =3D rb_subbuf_size(buffer); + unsigned int subbuf_size =3D rb_subbuf_size(buffer); struct ring_buffer_cpu_meta *meta; struct ring_buffer_meta *bmeta; - unsigned long ptr; - int nr_subbufs; + unsigned long ptr, nr_subbufs; =20 bmeta =3D buffer->meta; if (!bmeta) @@ -1731,7 +1730,7 @@ static void *rb_range_meta(struct trace_buffer *buffe= r, int nr_pages, int cpu) /* Return the start of subbufs given the meta pointer */ static void *rb_subbufs_from_meta(struct ring_buffer_cpu_meta *meta) { - int subbuf_size =3D meta->subbuf_size; + unsigned int subbuf_size =3D meta->subbuf_size; unsigned long ptr; =20 ptr =3D (unsigned long)meta; @@ -1746,8 +1745,8 @@ static void *rb_subbufs_from_meta(struct ring_buffer_= cpu_meta *meta) static void *rb_range_buffer(struct ring_buffer_per_cpu *cpu_buffer, int i= dx) { struct ring_buffer_cpu_meta *meta; + unsigned int subbuf_size; unsigned long ptr; - int subbuf_size; =20 meta =3D rb_range_meta(cpu_buffer->buffer, 0, cpu_buffer->cpu); if (!meta) @@ -1840,10 +1839,10 @@ static bool rb_meta_init(struct trace_buffer *buffe= r, int scratch_size) * must be the same. */ static bool rb_cpu_meta_valid(struct ring_buffer_cpu_meta *meta, int cpu, - struct trace_buffer *buffer, int nr_pages, + struct trace_buffer *buffer, unsigned long nr_pages, unsigned long *subbuf_mask) { - int subbuf_size =3D PAGE_SIZE; + unsigned int subbuf_size =3D PAGE_SIZE; unsigned long buffers_start; unsigned long buffers_end; int i; @@ -2231,7 +2230,8 @@ static void rb_meta_validate_events(struct ring_buffe= r_per_cpu *cpu_buffer) } } =20 -static void rb_range_meta_init(struct trace_buffer *buffer, int nr_pages, = int scratch_size) +static void rb_range_meta_init(struct trace_buffer *buffer, + unsigned long nr_pages, int scratch_size) { struct ring_buffer_cpu_meta *meta; unsigned long *subbuf_mask; @@ -2417,7 +2417,7 @@ static void *ring_buffer_desc_page(struct ring_buffer= _desc *desc, unsigned int p } =20 static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, - long nr_pages, struct list_head *pages) + unsigned long nr_pages, struct list_head *pages) { struct trace_buffer *buffer =3D cpu_buffer->buffer; struct ring_buffer_cpu_meta *meta =3D NULL; @@ -2545,7 +2545,7 @@ static int rb_allocate_pages(struct ring_buffer_per_c= pu *cpu_buffer, } =20 static struct ring_buffer_per_cpu * -rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu) +rb_allocate_cpu_buffer(struct trace_buffer *buffer, unsigned long nr_pages= , int cpu) { struct ring_buffer_per_cpu *cpu_buffer __free(kfree) =3D alloc_cpu_buffer(cpu); @@ -2702,8 +2702,8 @@ static void rb_test_inject_invalid_pages(struct trace= _buffer *buffer) struct ring_buffer_cpu_meta *meta; struct buffer_data_page *dpage; unsigned long entry_bytes =3D 0; + unsigned int subbuf_size; unsigned long ptr; - int subbuf_size; int invalid =3D 0; int cpu; int i; @@ -2773,8 +2773,8 @@ static struct trace_buffer *alloc_buffer(unsigned lon= g size, unsigned flags, struct ring_buffer_remote *remote) { struct trace_buffer *buffer __free(kfree) =3D NULL; - long nr_pages; - int subbuf_size; + unsigned int subbuf_size; + unsigned long nr_pages; int bsize; int cpu; int ret; @@ -2837,6 +2837,10 @@ static struct trace_buffer *alloc_buffer(unsigned lo= ng size, unsigned flags, */ nr_pages =3D (size - sizeof(struct ring_buffer_cpu_meta)) / (subbuf_size + sizeof(int)); + + /* limited by ring_buffer_cpu_meta::nr_subbufs */ + if (nr_pages > U32_MAX - 1) + goto fail_free_buffers; /* Need at least two pages plus the reader page */ if (nr_pages < 3) goto fail_free_buffers; @@ -2869,6 +2873,10 @@ static struct trace_buffer *alloc_buffer(unsigned lo= ng size, unsigned flags, /* The writer is remote. This ring-buffer is read-only */ atomic_inc(&buffer->record_disabled); nr_pages =3D desc->nr_page_va - 1; + + /* limited by ring_buffer_desc::nr_page_va */ + if (nr_pages > U32_MAX - 1) + goto fail_free_buffers; if (nr_pages < 2) goto fail_free_buffers; } else { @@ -7421,8 +7429,8 @@ int ring_buffer_subbuf_order_set(struct trace_buffer = *buffer, int order) struct ring_buffer_per_cpu *cpu_buffer; struct buffer_page *bpage, *tmp; unsigned int old_capacity; + unsigned long nr_pages; int old_order; - int nr_pages; int psize; int err; int cpu; @@ -7604,7 +7612,7 @@ static void rb_setup_ids_meta_page(struct ring_buffer= _per_cpu *cpu_buffer, struct buffer_page **subbuf_ids) { struct trace_buffer_meta *meta =3D cpu_buffer->meta_page; - unsigned int nr_subbufs =3D cpu_buffer->nr_pages + 1; + unsigned long nr_subbufs =3D cpu_buffer->nr_pages + 1; struct buffer_page *first_subbuf, *subbuf; int cnt =3D 0; int id =3D 0; @@ -7834,6 +7842,10 @@ int ring_buffer_map(struct trace_buffer *buffer, int= cpu, /* prevent another thread from changing buffer/sub-buffer sizes */ guard(mutex)(&buffer->mutex); =20 + /* limited by trace_buffer_meta::nr_subbufs */ + if (cpu_buffer->nr_pages > U32_MAX - 1) + return -E2BIG; + err =3D rb_alloc_meta_page(cpu_buffer); if (err) return err; --=20 2.55.0.691.gc56d675ccc-goog