FAILED: patch "[PATCH] tracing: Fix ignored return value of" failed to apply to 6.18-stable tree

FAILED: patch "[PATCH] tracing: Fix ignored return value of" failed to apply to 6.18-stable tree

[gregkh]

The patch below does not apply to the 6.18-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x 3110d09bb98e3ac66482a7b257548a1683ec6c1a
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026102126-obtuse-trimness-c3cc@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 3110d09bb98e3ac66482a7b257548a1683ec6c1a Mon Sep 17 00:00:00 2001
From: Dmitry Kandybka <d.kandybka@gmail.com>
Date: Mon, 28 Sep 2026 18:26:32 +0300
Subject: [PATCH] tracing: Fix ignored return value of
 resize_buffer_duplicate_size()

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>

diff --git a/kernel/trace/trace_snapshot.c b/kernel/trace/trace_snapshot.c
index 07b43c9863a2..4731ef7325a5 100644
--- a/kernel/trace/trace_snapshot.c
+++ b/kernel/trace/trace_snapshot.c
@@ -675,9 +675,12 @@ 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->snapshot_buffer,
 					&tr->array_buffer, iter->cpu_file);
+			if (ret < 0)
+				return ret;
+		}
 
 		ret = tracing_arm_snapshot_locked(tr);
 		if (ret)

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

[Sasha Levin]

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