# Re: \[PATCH\] ext4: fixed ext4\_calculate\_overhead() bug.

- From: Theodore Ts'o \<tytso@mit.edu\>
- Date: 2012-11-28 17:45:24 
- List: linux-ext4
- Page: https://ratatoskr.run/linux-ext4/2012/11/3964618
- Thread: https://ratatoskr.run/linux-ext4/2012/11/3964618/t.md

```text
On Wed, Nov 21, 2012 at 04:28:21PM -0800, Vahram Martirosyan wrote:
> The memset operation before check brings to a BUG.
> No need to memset the page with zeroes.
> 
> The patch removes the memset call in ext4_calculate_overhead() function.
> 
> Found by the Spruce system in cooperation with the KEDR Framework.
> 
> Signed-off-by: Vahram Martirosyan <redacted>

Applied, with a slightly rewritten commit description:

    ext4: fixed potential NULL dereference in ext4_calculate_overhead()
    
    The memset operation before check can cause a BUG if the memory
    allocation failed.  Since we are using get_zeroed_age, there is no
    need to use memset anyway.
    
    Found by the Spruce system in cooperation with the KEDR Framework.
    
    Signed-off-by: Vahram Martirosyan [ref]
    Signed-off-by: "Theodore Ts'o" [ref]

						- Ted
```