diff options
Diffstat (limited to 'drivers/char/mem.c')
| -rw-r--r-- | drivers/char/mem.c | 27 |
1 files changed, 22 insertions, 5 deletions
diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 6aefe5370e5b..052011bcf100 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -107,6 +107,8 @@ static ssize_t read_mem(struct file *file, char __user *buf, phys_addr_t p = *ppos; ssize_t read, sz; void *ptr; + char *bounce; + int err; if (p != *ppos) return 0; @@ -129,15 +131,22 @@ static ssize_t read_mem(struct file *file, char __user *buf, } #endif + bounce = kmalloc(PAGE_SIZE, GFP_KERNEL); + if (!bounce) + return -ENOMEM; + while (count > 0) { unsigned long remaining; int allowed; sz = size_inside_page(p, count); + err = -EPERM; allowed = page_is_allowed(p >> PAGE_SHIFT); if (!allowed) - return -EPERM; + goto failed; + + err = -EFAULT; if (allowed == 2) { /* Show zeros for restricted memory. */ remaining = clear_user(buf, sz); @@ -149,24 +158,32 @@ static ssize_t read_mem(struct file *file, char __user *buf, */ ptr = xlate_dev_mem_ptr(p); if (!ptr) - return -EFAULT; - - remaining = copy_to_user(buf, ptr, sz); + goto failed; + err = probe_kernel_read(bounce, ptr, sz); unxlate_dev_mem_ptr(p, ptr); + if (err) + goto failed; + + remaining = copy_to_user(buf, bounce, sz); } if (remaining) - return -EFAULT; + goto failed; buf += sz; p += sz; count -= sz; read += sz; } + kfree(bounce); *ppos += read; return read; + +failed: + kfree(bounce); + return err; } static ssize_t write_mem(struct file *file, const char __user *buf, |