nelsbrock/fun-linux-patches
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nelsbrock
2024-05-14 22:35:30 +02:00
commit 77f53012c2
2 changed files with 131 additions and 0 deletions
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literally_null.patch
+96
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@@ -0,0 +1,96 @@
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 3c6670cf905f..ec176debb778 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -30,6 +30,8 @@
#include <linux/uio.h>
#include <linux/uaccess.h>
#include <linux/security.h>
+#include <linux/minmax.h>
+#include <linux/printk.h>
#define DEVMEM_MINOR 1
#define DEVPORT_MINOR 4
@@ -428,7 +430,20 @@ static ssize_t write_port(struct file *file, const char __user *buf,
static ssize_t read_null(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
- return 0;
+ static const char content[] = "null\n";
+ size_t content_length = sizeof(content);
+
+ if (*ppos >= content_length)
+ return 0;
+
+ size_t copy_len = min(content_length - *ppos, count);
+ if (copy_to_user(buf, content + *ppos, copy_len)) {
+ pr_err("null: User copy failed\n");
+ return -EFAULT;
+ }
+
+ *ppos += copy_len;
+ return copy_len;
}
static ssize_t write_null(struct file *file, const char __user *buf,
@@ -437,33 +452,23 @@ static ssize_t write_null(struct file *file, const char __user *buf,
return count;
}
-static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to)
-{
- return 0;
-}
-
-static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from)
+static ssize_t write_iter_zero(struct kiocb *iocb, struct iov_iter *from)
{
size_t count = iov_iter_count(from);
iov_iter_advance(from, count);
return count;
}
-static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
+static int pipe_to_zero(struct pipe_inode_info *info, struct pipe_buffer *buf,
struct splice_desc *sd)
{
return sd->len;
}
-static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
+static ssize_t splice_write_zero(struct pipe_inode_info *pipe, struct file *out,
loff_t *ppos, size_t len, unsigned int flags)
{
- return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
-}
-
-static int uring_cmd_null(struct io_uring_cmd *ioucmd, unsigned int issue_flags)
-{
- return 0;
+ return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_zero);
}
static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter)
@@ -627,8 +632,6 @@ static int open_port(struct inode *inode, struct file *filp)
#define zero_lseek null_lseek
#define full_lseek null_lseek
#define write_zero write_null
-#define write_iter_zero write_iter_null
-#define splice_write_zero splice_write_null
#define open_mem open_port
static const struct file_operations __maybe_unused mem_fops = {
@@ -644,13 +647,8 @@ static const struct file_operations __maybe_unused mem_fops = {
};
static const struct file_operations null_fops = {
- .llseek = null_lseek,
.read = read_null,
.write = write_null,
- .read_iter = read_iter_null,
- .write_iter = write_iter_null,
- .splice_write = splice_write_null,
- .uring_cmd = uring_cmd_null,
};
static const struct file_operations __maybe_unused port_fops = {