[PATCH AUTOSEL 5.15 1/6] tracing: Add NULL checks for buffer in ring_buffer_free_read_page()

From: Jia-Ju Bai <redacted>

[ Upstream commit 3e4272b9954094907f16861199728f14002fcaf6 ]

In a previous commit 7433632c9ff6, buffer, buffer->buffers and
buffer->buffers[cpu] in ring_buffer_wake_waiters() can be NULL,
and thus the related checks are added.

However, in the same call stack, these variables are also used in
ring_buffer_free_read_page():

tracing_buffers_release()
  ring_buffer_wake_waiters(iter->array_buffer->buffer)
    cpu_buffer = buffer->buffers[cpu] -> Add checks by previous commit
  ring_buffer_free_read_page(iter->array_buffer->buffer)
    cpu_buffer = buffer->buffers[cpu] -> No check

Thus, to avod possible null-pointer derefernces, the related checks
should be added.

These results are reported by a static tool designed by myself.

Link: https://lkml.kernel.org/r/20230113125501.760324-1-baijiaju1990@gmail.com

Reported-by: TOTE Robot <redacted>
Signed-off-by: Jia-Ju Bai <redacted>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/trace/ring_buffer.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index ffc8696e67467..41ed07e2cbc05 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c

@@ -5568,11 +5568,16 @@ EXPORT_SYMBOL_GPL(ring_buffer_alloc_read_page);
  */
 void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, void *data)
 {
-	struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
+	struct ring_buffer_per_cpu *cpu_buffer;
 	struct buffer_data_page *bpage = data;
 	struct page *page = virt_to_page(bpage);
 	unsigned long flags;
 
+	if (!buffer || !buffer->buffers || !buffer->buffers[cpu])
+		return;
+
+	cpu_buffer = buffer->buffers[cpu];
+
 	/* If the page is still in use someplace else, we can't reuse it */
 	if (page_ref_count(page) > 1)
 		goto out;

-- 
2.39.2

From: Souradeep Chowdhury <quic_schowdhu@quicinc.com>

[ Upstream commit 6c40624930c58529185a257380442547580ed837 ]

The Data Capture and Compare(DCC) is a debugging tool that uses the bootconfig
for configuring the register values during boot-time. Increase the max nodes
supported by bootconfig to cater to the requirements of the Data Capture and
Compare Driver.

Link: https://lore.kernel.org/all/1674536682-18404-1-git-send-email-quic_schowdhu@quicinc.com/

Signed-off-by: Souradeep Chowdhury <quic_schowdhu@quicinc.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/bootconfig.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/bootconfig.h b/include/linux/bootconfig.h
index 537e1b991f115..5296fbb8408ca 100644
--- a/include/linux/bootconfig.h
+++ b/include/linux/bootconfig.h

@@ -49,7 +49,7 @@ struct xbc_node {
 /* Maximum size of boot config is 32KB - 1 */
 #define XBC_DATA_MAX	(XBC_VALUE - 1)
 
-#define XBC_NODE_MAX	1024
+#define XBC_NODE_MAX	8192
 #define XBC_KEYLEN_MAX	256
 #define XBC_DEPTH_MAX	16
 

-- 
2.39.2