FAILED: patch "[PATCH] perf: Require kernel access for text poke events" failed to apply to 7.2-stable tree

The patch below does not apply to the 7.2-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 <[email protected]>.

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-7.2.y
git checkout FETCH_HEAD
git cherry-pick -x 357e8a77a501d96c9517f01f4a211eed5e9c9184
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026100516-douche-preview-30a6@gregkh' --subject-prefix 'PATCH 7.2.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From 357e8a77a501d96c9517f01f4a211eed5e9c9184 Mon Sep 17 00:00:00 2001
From: Zhengchuan Liang <[email protected]>
Date: Mon, 28 Sep 2026 10:59:35 -0700
Subject: [PATCH] perf: Require kernel access for text poke events

Perf events with exclude_kernel=1 can be opened without kernel perf access. However, exclude_kernel does not suppress text-poke sideband records. Every PERF_RECORD_TEXT_POKE is marked PERF_RECORD_MISC_KERNEL and contains a raw kernel instruction address.

An unprivileged task can therefore open and mmap a task-local software event with text_poke=1. Both opening a count-only tracepoint event and configuring UDP GRO for ESP-in-UDP cause updates to inline static calls; the observer receives the relocated addresses of the modified instructions. For a known kernel image, any such address reveals the runtime kernel text base despite KASLR.

Call perf_allow_kernel() whenever attr.text_poke is set, regardless of exclude_kernel. Events that neither monitor kernel execution nor request text-poke records retain their existing permissions.

index 3aa223595e7d..7846d70be57f 100644
@@ -13906,7 +13906,7 @@ SYSCALL_DEFINE5(perf_event_open,
 	if (err)
 		return err;
 
-	if (!attr.exclude_kernel ||
+	if (!attr.exclude_kernel || attr.text_poke ||
 	    ((attr.sample_type & PERF_SAMPLE_CALLCHAIN) &&
 	     !attr.exclude_callchain_kernel)) {
 		err = perf_allow_kernel();

From: Dapeng Mi <[email protected]>

[ Upstream commit a4573a3838ae4fc73b70019cfa1dac9aaea7cc2f ]

perf_event_open() currently gates perf_allow_kernel() only on !attr.exclude_kernel.

However, users can still request kernel callchain collection with attr.exclude_callchain_kernel == 0 even when attr.exclude_kernel == 1. That still requires kernel profiling privilege, but the existing check does not enforce it.

Update the permission check to call perf_allow_kernel() when either kernel sampling is requested or kernel callchains are requested.

This keeps permission checks aligned with requested data and prevents unprivileged use of kernel callchain capture.

Stable-dep-of: 357e8a77a501 ("perf: Require kernel access for text poke events")

---
 kernel/events/core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

index 8a7fcb902a9f7..3c3166d50ec7b 100644
@@ -13882,7 +13882,9 @@ SYSCALL_DEFINE5(perf_event_open,
 	if (err)
 		return err;
 
-	if (!attr.exclude_kernel) {
+	if (!attr.exclude_kernel ||
+	    ((attr.sample_type & PERF_SAMPLE_CALLCHAIN) &&
+	     !attr.exclude_callchain_kernel)) {
 		err = perf_allow_kernel();
 		if (err)
 			return err;

2.53.0

From: Zhengchuan Liang <[email protected]>

[ Upstream commit 357e8a77a501d96c9517f01f4a211eed5e9c9184 ]

Perf events with exclude_kernel=1 can be opened without kernel perf access. However, exclude_kernel does not suppress text-poke sideband records. Every PERF_RECORD_TEXT_POKE is marked PERF_RECORD_MISC_KERNEL and contains a raw kernel instruction address.

An unprivileged task can therefore open and mmap a task-local software event with text_poke=1. Both opening a count-only tracepoint event and configuring UDP GRO for ESP-in-UDP cause updates to inline static calls; the observer receives the relocated addresses of the modified instructions. For a known kernel image, any such address reveals the runtime kernel text base despite KASLR.

Call perf_allow_kernel() whenever attr.text_poke is set, regardless of exclude_kernel. Events that neither monitor kernel execution nor request text-poke records retain their existing permissions.

---
 kernel/events/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 3c3166d50ec7b..4959b287f589d 100644
@@ -13882,7 +13882,7 @@ SYSCALL_DEFINE5(perf_event_open,
 	if (err)
 		return err;
 
-	if (!attr.exclude_kernel ||
+	if (!attr.exclude_kernel || attr.text_poke ||
 	    ((attr.sample_type & PERF_SAMPLE_CALLCHAIN) &&
 	     !attr.exclude_callchain_kernel)) {
 		err = perf_allow_kernel();

2.53.0