As Linus mentioned in [1], currently we have several memcpy() use-cases
which use 'current->comm' to copy the task name over to local copies.
For an example:

 ...
 char comm[TASK_COMM_LEN];
 memcpy(comm, current->comm, TASK_COMM_LEN);
 ...

These should be rather calling a wrappper like "get_task_array()",
which is implemented as:

   static __always_inline void
       __cstr_array_copy(char *dst,
            const char *src, __kernel_size_t size)
   {
        memcpy(dst, src, size);
        dst[size] = 0;
   }

   #define get_task_array(dst,src) \
      __cstr_array_copy(dst, src, __must_be_array(dst))

The relevant 'memcpy()' users were identified using the following search
pattern:
 $ git grep 'memcpy.*->comm\>'

Link: https://lore.kernel.org/all/CAHk-=wi5c=_-FBGo_88CowJd_F-Gi6Ud9d=TALm65ReN7YjrMw@mail.gmail.com/ (local) #1

Signed-off-by: Bhupesh <redacted>
---
 include/linux/coredump.h                      |  2 +-
 include/linux/sched.h                         | 32 +++++++++++++++++++
 include/linux/tracepoint.h                    |  4 +--
 include/trace/events/block.h                  | 10 +++---
 include/trace/events/oom.h                    |  2 +-
 include/trace/events/osnoise.h                |  2 +-
 include/trace/events/sched.h                  | 13 ++++----
 include/trace/events/signal.h                 |  2 +-
 include/trace/events/task.h                   |  4 +--
 tools/bpf/bpftool/pids.c                      |  6 ++--
 .../bpf/test_kmods/bpf_testmod-events.h       |  2 +-
 11 files changed, 54 insertions(+), 25 deletions(-)

diff --git a/include/linux/coredump.h b/include/linux/coredump.h
index 68861da4cf7c..bcee0afc5eaf 100644
--- a/include/linux/coredump.h
+++ b/include/linux/coredump.h

@@ -54,7 +54,7 @@ extern void vfs_coredump(const kernel_siginfo_t *siginfo);
 	do {	\
 		char comm[TASK_COMM_LEN];	\
 		/* This will always be NUL terminated. */ \
-		memcpy(comm, current->comm, sizeof(comm)); \
+		get_task_array(comm, current->comm); \
 		printk_ratelimited(Level "coredump: %d(%*pE): " Format "\n",	\
 			task_tgid_vnr(current), (int)strlen(comm), comm, ##__VA_ARGS__);	\
 	} while (0)	\

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5a58c1270474..d26d1dfb9904 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h

@@ -1960,12 +1960,44 @@ extern void wake_up_new_task(struct task_struct *tsk);
 
 extern void kick_process(struct task_struct *tsk);
 
+/*
+ * - Why not use task_lock()?
+ *   User space can randomly change their names anyway, so locking for readers
+ *   doesn't make sense. For writers, locking is probably necessary, as a race
+ *   condition could lead to long-term mixed results.
+ *   The logic inside __set_task_comm() should ensure that the task comm is
+ *   always NUL-terminated and zero-padded. Therefore the race condition between
+ *   reader and writer is not an issue.
+ */
+
 extern void __set_task_comm(struct task_struct *tsk, const char *from, bool exec);
 #define set_task_comm(tsk, from) ({			\
 	BUILD_BUG_ON(sizeof(from) < TASK_COMM_LEN);	\
 	__set_task_comm(tsk, from, false);		\
 })
 
+/*
+ * 'get_task_array' can be 'data-racy' in the destination and
+ * should not be used for cases where a 'stable NUL at the end'
+ * is needed. Its better to use strscpy and friends for such
+ * use-cases.
+ *
+ * It is suited mainly for a 'just copy comm to a constant-sized
+ * array' case - especially in performance sensitive use-cases,
+ * like tracing.
+ */
+
+static __always_inline void
+	__cstr_array_copy(char *dst, const char *src,
+			  __kernel_size_t size)
+{
+	memcpy(dst, src, size);
+	dst[size] = 0;
+}