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kernel_modules/mmap.c: treat read offset to prevent infinite loop on cat /proc/lkmc_mmap

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Ciro Santilli 六四事件 法轮功
2020-07-25 01:00:00 +00:00
parent b5d6fcd7d8
commit 2ea5e17d23
1 changed files with 12 additions and 6 deletions
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14
kernel_modules/mmap.c
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@@ -39,7 +39,7 @@ static vm_fault_t vm_fault(struct vm_fault *vmf)
return 0; return 0;
} }
/* Aftr mmap. TODO vs mmap, when can this happen at a different time than mmap? */ /* After mmap. TODO vs mmap, when can this happen at a different time than mmap? */
static void vm_open(struct vm_area_struct *vma) static void vm_open(struct vm_area_struct *vma)
{ {
pr_info("vm_open\n"); pr_info("vm_open\n");
@@ -78,13 +78,19 @@ static int open(struct inode *inode, struct file *filp)
static ssize_t read(struct file *filp, char __user *buf, size_t len, loff_t *off) static ssize_t read(struct file *filp, char __user *buf, size_t len, loff_t *off)
{ {
struct mmap_info *info; struct mmap_info *info;
int ret; ssize_t ret;
pr_info("read\n"); pr_info("read\n");
if ((size_t)BUFFER_SIZE <= *off) {
ret = 0;
} else {
info = filp->private_data; info = filp->private_data;
ret = min(len, (size_t)BUFFER_SIZE); ret = min(len, (size_t)BUFFER_SIZE - (size_t)*off);
if (copy_to_user(buf, info->data, ret)) { if (copy_to_user(buf, info->data + *off, ret)) {
ret = -EFAULT; ret = -EFAULT;
} else {
*off += ret;
}
} }
return ret; return ret;
} }