[PATCH 6.18.y] tracing: Fix ignored return value of resize_buffer_duplicate_size()

[Sasha Levin <sashal@kernel.org>]

From: Dmitry Kandybka <d.kandybka@gmail.com>

[ Upstream commit 3110d09bb98e3ac66482a7b257548a1683ec6c1a ]

When tr->allocated_snapshot is true, resize_buffer_duplicate_size() is
called to update the snapshot buffer size. However, its return value was
not checked. In case of a failed resize this could lead next snapshot
being incomplete.

Add resize_buffer_duplicate_size() result check and return error if
resize fails.

Compile tested only.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260928152634.4354-1-d.kandybka@gmail.com
Fixes: 180e4e390978 ("tracing: Add snapshot refcount")
Signed-off-by: Dmitry Kandybka <d.kandybka@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
[ sashal: Adapted snapshot_buffer access to max_buffer in the existing snapshot handler. ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/trace/trace.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 45b24fe040ad8..a76743475e9f4 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7811,9 +7811,12 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt,
 		if (iter->cpu_file != RING_BUFFER_ALL_CPUS)
 			return -EINVAL;
 #endif
-		if (tr->allocated_snapshot)
+		if (tr->allocated_snapshot) {
 			ret = resize_buffer_duplicate_size(&tr->max_buffer,
 					&tr->array_buffer, iter->cpu_file);
+			if (ret < 0)
+				return ret;
+		}
 
 		ret = tracing_arm_snapshot_locked(tr);
 		if (ret)
-- 
2.53.0