ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 49 insertions, 0 deletions

diff --git a/lib/zlib_inflate/infutil.c b/lib/zlib_inflate/infutil.c
new file mode 100644
index 000000000..12169aacd
--- /dev/null
+++ b/lib/zlib_inflate/infutil.c
@@ -0,0 +1,49 @@
+#include <linux/zutil.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+
+/* Utility function: initialize zlib, unpack binary blob, clean up zlib,
+ * return len or negative error code.
+ */
+int zlib_inflate_blob(void *gunzip_buf, unsigned int sz,
+		      const void *buf, unsigned int len)
+{
+	const u8 *zbuf = buf;
+	struct z_stream_s *strm;
+	int rc;
+
+	rc = -ENOMEM;
+	strm = kmalloc_obj(*strm);
+	if (strm == NULL)
+		goto gunzip_nomem1;
+	strm->workspace = kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
+	if (strm->workspace == NULL)
+		goto gunzip_nomem2;
+
+	/* gzip header (1f,8b,08... 10 bytes total + possible asciz filename)
+	 * expected to be stripped from input
+	 */
+	strm->next_in = zbuf;
+	strm->avail_in = len;
+	strm->next_out = gunzip_buf;
+	strm->avail_out = sz;
+
+	rc = zlib_inflateInit2(strm, -MAX_WBITS);
+	if (rc == Z_OK) {
+		rc = zlib_inflate(strm, Z_FINISH);
+		/* after Z_FINISH, only Z_STREAM_END is "we unpacked it all" */
+		if (rc == Z_STREAM_END)
+			rc = sz - strm->avail_out;
+		else
+			rc = -EINVAL;
+		zlib_inflateEnd(strm);
+	} else
+		rc = -EINVAL;
+
+	kfree(strm->workspace);
+gunzip_nomem2:
+	kfree(strm);
+gunzip_nomem1:
+	return rc; /* returns Z_OK (0) if successful */
+}