Move the parsing into ddebug_proc_write_buf() and implement
->proc_write_buf() with it so procfs copies in what is written before
it pins the entry. The debugfs file keeps copying in itself. Writes
larger than USER_BUF_PAGE - 1 bytes to the procfs file now fail with
-EINVAL from procfs instead of -E2BIG.
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
---
lib/dynamic_debug.c | 34 ++++++++++++++++++++++------------
1 file changed, 22 insertions(+), 12 deletions(-)
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 64a211290872..1d6012c9eb41 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -1002,11 +1002,28 @@ __setup("dyndbg=", dyndbg_setup);
* command text from userspace, parses and executes it.
*/
#define USER_BUF_PAGE 4096
+
+static ssize_t ddebug_proc_write_buf(struct file *file, char *buf, size_t len,
+ loff_t *offp)
+{
+ int ret;
+
+ if (len == 0)
+ return 0;
+ v2pr_info("read %zu bytes from userspace\n", len);
+
+ ret = ddebug_exec_queries(buf, NULL);
+ if (ret < 0)
+ return ret;
+
+ *offp += len;
+ return len;
+}
+
static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf,
size_t len, loff_t *offp)
{
- char *tmpbuf;
- int ret;
+ char *tmpbuf __free(kfree) = NULL;
if (len == 0)
return 0;@@ -1017,15 +1034,7 @@ static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf,
tmpbuf = memdup_user_nul(ubuf, len);
if (IS_ERR(tmpbuf))
return PTR_ERR(tmpbuf);
- v2pr_info("read %zu bytes from userspace\n", len);
-
- ret = ddebug_exec_queries(tmpbuf, NULL);
- kfree(tmpbuf);
- if (ret < 0)
- return ret;
-
- *offp += len;
- return len;
+ return ddebug_proc_write_buf(file, tmpbuf, len, offp);
}
/*@@ -1196,7 +1205,8 @@ static const struct file_operations ddebug_proc_fops = {
static const struct proc_ops proc_fops = {
.proc_seq_ops = &ddebug_proc_seqops,
.proc_state_size = sizeof(struct ddebug_iter),
- .proc_write = ddebug_proc_write
+ .proc_write_buf = ddebug_proc_write_buf,
+ .proc_write_size = USER_BUF_PAGE - 1,
};
static void ddebug_attach_module_classes(struct ddebug_table *dt,
--
2.53.0