Re: [PATCH v2] crypto: ixp4xx - fix buffer chain unwind on allocation failure

[Herbert Xu <herbert@gondor.apana.org.au>]

On Thu, Apr 23, 2026 at 07:19:56PM +0800, Ruoyu Wang wrote:
> chainup_buffers() builds a linked list of buffer descriptors for a
> scatterlist. If dma_pool_alloc() fails while constructing the list, the
> current code sets buf to NULL and later dereferences it unconditionally
> at the end of the function:
> 
>   buf->next = NULL;
>   buf->phys_next = 0;
> 
> This can lead to a null-pointer dereference on allocation failure.
> 
> If the failure happens after part of the descriptor chain has already
> been allocated and DMA-mapped, the partially constructed chain also
> needs to be released.
> 
> Fix this by terminating the partially constructed chain on allocation
> failure and letting the callers unwind it via their existing cleanup
> paths. Also fix ablk_perform() to preserve the hook pointers before
> checking for failure, so partially built chains can be freed correctly.
> 
> Signed-off-by: Ruoyu Wang <ruoyuw560@gmail.com>
> ---
> v2:
> - Keep the unwind path in the callers, per Herbert Xu's feedback.
> - Terminate the partial chain before returning NULL on allocation failure.
> - Save the hook pointers in ablk_perform() before checking the return value.
> - Thanks to Herbert Xu for the review.
> 
>  drivers/crypto/intel/ixp4xx/ixp4xx_crypto.c | 25 ++++++++++++---------
>  1 file changed, 14 insertions(+), 11 deletions(-)

Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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