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 <benjamin@xxxxxxxxxxx>
---
drivers/md/md.c | 21 ++++++++++-----------
1 file changed, 10 insertions(+), 11 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 80879dc..382bdbc 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5766,22 +5766,21 @@ 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) {
+ 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));
+ }
spin_unlock(&mddev->lock);
if (err == 0 &&
--
2.3.6
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