[PATCH 2/2] ext4: Fix zalloc()

[Heinrich Schuchardt]

On 02.07.24 21:42, Richard Weinberger wrote:
> The zalloc() function suffers from two problems.
> 1. If memalign() fails it will return NULL and memset() will use a NULL pointer.
> 2. memalign() itself seems to crash when more than 2^32 bytes are requested.
>
> So, check the return value of memalign() and allocate only of size is less than
> CONFIG_SYS_MALLOC_LEN.
>
> Signed-off-by: Richard Weinberger <richard at nod.at>
> ---
> FWIW, I didn't investigate further why memalign() fails for large sizes.
> Maybe this is an issue on it's own.
>
> Thanks,
> //richard
> ---
>   fs/ext4/ext4_common.h | 10 ++++++++--
>   1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/ext4_common.h b/fs/ext4/ext4_common.h
> index 84500e990a..0d1f72ae01 100644
> --- a/fs/ext4/ext4_common.h
> +++ b/fs/ext4/ext4_common.h
> @@ -43,8 +43,14 @@
>
>   static inline void *zalloc(size_t size)
>   {
> -	void *p = memalign(ARCH_DMA_MINALIGN, size);
> -	memset(p, 0, size);
> +	void *p = NULL;
> +
> +	if (size < CONFIG_SYS_MALLOC_LEN)
> +		p = memalign(ARCH_DMA_MINALIGN, size);

Memalign() is called in many code locations.

If memalign() has a bug, it needs to be fixed in memalign. We should not
try to work around it in all callers.

Best regards

Heinrich

> +
> +	if (p)
> +		memset(p, 0, size);
> +
>   	return p;
>   }
>