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improve memfile a bit with missing slab and dyn_arr_reserve write out of mem error check

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And don't do wrong deadlock on write error.
This commit is contained in:
Ciro Santilli
2025-05-01 12:30:19 +01:00
parent c3a6c7e85b
commit dc677f62eb
1 changed files with 14 additions and 5 deletions
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19
kernel_modules/memfile.c
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@@ -6,7 +6,8 @@
#include <linux/kernel.h> /* min */ #include <linux/kernel.h> /* min */
#include <linux/module.h> #include <linux/module.h>
#include <linux/printk.h> /* printk */ #include <linux/printk.h> /* printk */
#include <linux/string.h> /* strcpy */ #include <linux/slab.h> /* kvzalloc, kvrealloc, kvfree */
#include <linux/string.h> /* memset */
#include <linux/uaccess.h> /* copy_from_user, copy_to_user */ #include <linux/uaccess.h> /* copy_from_user, copy_to_user */
#include <linux/rwsem.h> #include <linux/rwsem.h>
#include <uapi/linux/stat.h> /* S_IRUSR */ #include <uapi/linux/stat.h> /* S_IRUSR */
@@ -43,7 +44,7 @@ int dyn_arr_reserve(dyn_arr_t *a, size_t off, size_t len);
int dyn_arr_reserve(dyn_arr_t *a, size_t off, size_t len) int dyn_arr_reserve(dyn_arr_t *a, size_t off, size_t len)
{ {
size_t new_used, new_size; size_t new_used, new_size;
new_used = off + len; new_used = off + len;
if (new_used > a->_size) { if (new_used > a->_size) {
new_size = new_used * 2; new_size = new_used * 2;
@@ -99,10 +100,12 @@ static ssize_t read(struct file *filp, char __user *buf, size_t len, loff_t *off
ret = min(len, data.used - (size_t)*off); ret = min(len, data.used - (size_t)*off);
if (copy_to_user(buf, data.buf + *off, ret)) { if (copy_to_user(buf, data.buf + *off, ret)) {
ret = -EFAULT; ret = -EFAULT;
goto out;
} else { } else {
*off += ret; *off += ret;
} }
} }
out:
up_read(&rwsem); up_read(&rwsem);
if (log) pr_info("read ret:=%lld\n", (long long)ret); if (log) pr_info("read ret:=%lld\n", (long long)ret);
return ret; return ret;
@@ -114,15 +117,21 @@ static ssize_t write(struct file *filp, const char __user *buf, size_t len, loff
if (log) pr_info("write len=%zu off=%lld\n", len, (long long)*off); if (log) pr_info("write len=%zu off=%lld\n", len, (long long)*off);
down_write(&rwsem); down_write(&rwsem);
dyn_arr_reserve(&data, *off, len); ret = dyn_arr_reserve(&data, *off, len);
if (ret) {
ret = -ENOSPC;
goto out;
}
if (copy_from_user(data.buf + *off, buf, len)) { if (copy_from_user(data.buf + *off, buf, len)) {
ret = -EFAULT; ret = -EFAULT;
goto out;
} else { } else {
ret = len; ret = len;
*off += ret; *off += ret;
} }
up_write(&rwsem); out:
if (log) pr_info("write ret:=%lld\n", (long long)ret); if (log) pr_info("write ret:=%lld\n", (long long)ret);
up_write(&rwsem);
return ret; return ret;
} }
@@ -168,7 +177,7 @@ static const struct file_operations fops = {
static int myinit(void) static int myinit(void)
{ {
int ret; int ret;
ret = dyn_arr_init(&data, 1); ret = dyn_arr_init(&data, 1);
if (ret) if (ret)
return ret; return ret;