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, 222 insertions, 0 deletions

diff --git a/fs/jffs2/compr_zlib.c b/fs/jffs2/compr_zlib.c
new file mode 100644
index 000000000..5698dae5d
--- /dev/null
+++ b/fs/jffs2/compr_zlib.c
@@ -0,0 +1,222 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2001-2007 Red Hat, Inc.
+ * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
+ *
+ * Created by David Woodhouse <dwmw2@infradead.org>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ */
+
+#if !defined(__KERNEL__) && !defined(__ECOS)
+#error "The userspace support got too messy and was removed. Update your mkfs.jffs2"
+#endif
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/zlib.h>
+#include <linux/zutil.h>
+#include "nodelist.h"
+#include "compr.h"
+
+	/* Plan: call deflate() with avail_in == *sourcelen,
+		avail_out = *dstlen - 12 and flush == Z_FINISH.
+		If it doesn't manage to finish,	call it again with
+		avail_in == 0 and avail_out set to the remaining 12
+		bytes for it to clean up.
+	   Q: Is 12 bytes sufficient?
+	*/
+#define STREAM_END_SPACE 12
+
+static DEFINE_MUTEX(deflate_mutex);
+static DEFINE_MUTEX(inflate_mutex);
+static z_stream inf_strm, def_strm;
+
+#ifdef __KERNEL__ /* Linux-only */
+#include <linux/vmalloc.h>
+#include <linux/init.h>
+#include <linux/mutex.h>
+
+static int __init alloc_workspaces(void)
+{
+	def_strm.workspace = vmalloc(zlib_deflate_workspacesize(MAX_WBITS,
+							MAX_MEM_LEVEL));
+	if (!def_strm.workspace)
+		return -ENOMEM;
+
+	jffs2_dbg(1, "Allocated %d bytes for deflate workspace\n",
+		  zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL));
+	inf_strm.workspace = vmalloc(zlib_inflate_workspacesize());
+	if (!inf_strm.workspace) {
+		vfree(def_strm.workspace);
+		return -ENOMEM;
+	}
+	jffs2_dbg(1, "Allocated %d bytes for inflate workspace\n",
+		  zlib_inflate_workspacesize());
+	return 0;
+}
+
+static void free_workspaces(void)
+{
+	vfree(def_strm.workspace);
+	vfree(inf_strm.workspace);
+}
+#else
+#define alloc_workspaces() (0)
+#define free_workspaces() do { } while(0)
+#endif /* __KERNEL__ */
+
+static int jffs2_zlib_compress(unsigned char *data_in,
+			       unsigned char *cpage_out,
+			       uint32_t *sourcelen, uint32_t *dstlen)
+{
+	int ret;
+
+	if (*dstlen <= STREAM_END_SPACE)
+		return -1;
+
+	mutex_lock(&deflate_mutex);
+
+	if (Z_OK != zlib_deflateInit(&def_strm, 3)) {
+		pr_warn("deflateInit failed\n");
+		mutex_unlock(&deflate_mutex);
+		return -1;
+	}
+
+	def_strm.next_in = data_in;
+	def_strm.total_in = 0;
+
+	def_strm.next_out = cpage_out;
+	def_strm.total_out = 0;
+
+	while (def_strm.total_out < *dstlen - STREAM_END_SPACE && def_strm.total_in < *sourcelen) {
+		def_strm.avail_out = *dstlen - (def_strm.total_out + STREAM_END_SPACE);
+		def_strm.avail_in = min_t(unsigned long,
+			(*sourcelen-def_strm.total_in), def_strm.avail_out);
+		jffs2_dbg(1, "calling deflate with avail_in %ld, avail_out %ld\n",
+			  def_strm.avail_in, def_strm.avail_out);
+		ret = zlib_deflate(&def_strm, Z_PARTIAL_FLUSH);
+		jffs2_dbg(1, "deflate returned with avail_in %ld, avail_out %ld, total_in %ld, total_out %ld\n",
+			  def_strm.avail_in, def_strm.avail_out,
+			  def_strm.total_in, def_strm.total_out);
+		if (ret != Z_OK) {
+			jffs2_dbg(1, "deflate in loop returned %d\n", ret);
+			zlib_deflateEnd(&def_strm);
+			mutex_unlock(&deflate_mutex);
+			return -1;
+		}
+	}
+	def_strm.avail_out += STREAM_END_SPACE;
+	def_strm.avail_in = 0;
+	ret = zlib_deflate(&def_strm, Z_FINISH);
+	zlib_deflateEnd(&def_strm);
+
+	if (ret != Z_STREAM_END) {
+		jffs2_dbg(1, "final deflate returned %d\n", ret);
+		ret = -1;
+		goto out;
+	}
+
+	if (def_strm.total_out >= def_strm.total_in) {
+		jffs2_dbg(1, "zlib compressed %ld bytes into %ld; failing\n",
+			  def_strm.total_in, def_strm.total_out);
+		ret = -1;
+		goto out;
+	}
+
+	jffs2_dbg(1, "zlib compressed %ld bytes into %ld\n",
+		  def_strm.total_in, def_strm.total_out);
+
+	*dstlen = def_strm.total_out;
+	*sourcelen = def_strm.total_in;
+	ret = 0;
+ out:
+	mutex_unlock(&deflate_mutex);
+	return ret;
+}
+
+static int jffs2_zlib_decompress(unsigned char *data_in,
+				 unsigned char *cpage_out,
+				 uint32_t srclen, uint32_t destlen)
+{
+	int ret;
+	int wbits = MAX_WBITS;
+
+	mutex_lock(&inflate_mutex);
+
+	inf_strm.next_in = data_in;
+	inf_strm.avail_in = srclen;
+	inf_strm.total_in = 0;
+
+	inf_strm.next_out = cpage_out;
+	inf_strm.avail_out = destlen;
+	inf_strm.total_out = 0;
+
+	/* If it's deflate, and it's got no preset dictionary, then
+	   we can tell zlib to skip the adler32 check. */
+	if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
+	    ((data_in[0] & 0x0f) == Z_DEFLATED) &&
+	    !(((data_in[0]<<8) + data_in[1]) % 31)) {
+
+		jffs2_dbg(2, "inflate skipping adler32\n");
+		wbits = -((data_in[0] >> 4) + 8);
+		inf_strm.next_in += 2;
+		inf_strm.avail_in -= 2;
+	} else {
+		/* Let this remain D1 for now -- it should never happen */
+		jffs2_dbg(1, "inflate not skipping adler32\n");
+	}
+
+
+	if (Z_OK != zlib_inflateInit2(&inf_strm, wbits)) {
+		pr_warn("inflateInit failed\n");
+		mutex_unlock(&inflate_mutex);
+		return 1;
+	}
+
+	while((ret = zlib_inflate(&inf_strm, Z_FINISH)) == Z_OK)
+		;
+	if (ret != Z_STREAM_END) {
+		pr_notice("inflate returned %d\n", ret);
+	}
+	zlib_inflateEnd(&inf_strm);
+	mutex_unlock(&inflate_mutex);
+	return 0;
+}
+
+static struct jffs2_compressor jffs2_zlib_comp = {
+    .priority = JFFS2_ZLIB_PRIORITY,
+    .name = "zlib",
+    .compr = JFFS2_COMPR_ZLIB,
+    .compress = &jffs2_zlib_compress,
+    .decompress = &jffs2_zlib_decompress,
+#ifdef JFFS2_ZLIB_DISABLED
+    .disabled = 1,
+#else
+    .disabled = 0,
+#endif
+};
+
+int __init jffs2_zlib_init(void)
+{
+    int ret;
+
+    ret = alloc_workspaces();
+    if (ret)
+	    return ret;
+
+    ret = jffs2_register_compressor(&jffs2_zlib_comp);
+    if (ret)
+	    free_workspaces();
+
+    return ret;
+}
+
+void jffs2_zlib_exit(void)
+{
+    jffs2_unregister_compressor(&jffs2_zlib_comp);
+    free_workspaces();
+}