From 77ba0569d4c8389c0a2162ab0c7c16a6f3b199e4 Mon Sep 17 00:00:00 2001 From: Benjamin Randazzo Date: Sat, 25 Jul 2015 16:36:50 +0200 Subject: md: use kzalloc() when bitmap is disabled In drivers/md/md.c get_bitmap_file() uses kmalloc() for creating a mdu_bitmap_file_t called "file". 5769 file = kmalloc(sizeof(*file), GFP_NOIO); 5770 if (!file) 5771 return -ENOMEM; This structure is copied to user space at the end of the function. 5786 if (err == 0 && 5787 copy_to_user(arg, file, sizeof(*file))) 5788 err = -EFAULT But if bitmap is disabled only the first byte of "file" is initialized with zero, so it's possible to read some bytes (up to 4095) of kernel space memory from user space. This is an information leak. 5775 /* bitmap disabled, zero the first byte and copy out */ 5776 if (!mddev->bitmap_info.file) 5777 file->pathname[0] = '\0'; Signed-off-by: Benjamin Randazzo Signed-off-by: NeilBrown diff --git a/drivers/md/md.c b/drivers/md/md.c index ce4cb8b..cdc080b 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -5765,22 +5765,22 @@ static int get_bitmap_file(struct mddev *mddev, void __user * arg) char *ptr; int err; - file = kmalloc(sizeof(*file), GFP_NOIO); + file = kzalloc(sizeof(*file), GFP_NOIO); if (!file) return -ENOMEM; err = 0; spin_lock(&mddev->lock); - /* bitmap disabled, zero the first byte and copy out */ - if (!mddev->bitmap_info.file) - file->pathname[0] = '\0'; - else if ((ptr = file_path(mddev->bitmap_info.file, - file->pathname, sizeof(file->pathname))), - IS_ERR(ptr)) - err = PTR_ERR(ptr); - else - memmove(file->pathname, ptr, - sizeof(file->pathname)-(ptr-file->pathname)); + /* bitmap enabled */ + if (mddev->bitmap_info.file) { + ptr = file_path(mddev->bitmap_info.file, file->pathname, + sizeof(file->pathname)); + if (IS_ERR(ptr)) + err = PTR_ERR(ptr); + else + memmove(file->pathname, ptr, + sizeof(file->pathname)-(ptr-file->pathname)); + } spin_unlock(&mddev->lock); if (err == 0 && -- cgit v0.10.2