diff options
| author | Carlos Maiolino | 2020-01-09 14:30:45 +0100 |
|---|---|---|
| committer | Al Viro | 2020-02-03 08:05:58 -0500 |
| commit | 324282c0252a44a97d628813e30ea7258940d469 (patch) | |
| tree | a22618816695a6fa7e078319ba003be102bba12f | |
| parent | 0d89fdae2afe833dd3025edd8c8287675d45c74e (diff) | |
fibmap: Reject negative block numbers
FIBMAP receives an integer from userspace which is then implicitly converted
into sector_t to be passed to bmap(). No check is made to ensure userspace
didn't send a negative block number, which can end up in an underflow, and
returning to userspace a corrupted block address.
As a side-effect, the underflow caused by a negative block here, will
trigger the WARN() in iomap_bmap_actor(), which is how this issue was
first discovered.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| -rw-r--r-- | fs/ioctl.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/ioctl.c b/fs/ioctl.c index 13327862f278..0be9bee9ff8f 100644 --- a/fs/ioctl.c +++ b/fs/ioctl.c @@ -65,6 +65,9 @@ static int ioctl_fibmap(struct file *filp, int __user *p) if (error) return error; + if (ur_block < 0) + return -EINVAL; + block = ur_block; error = bmap(inode, &block); |