linux-kernel - Re: [PATCH] crypto: scomp - Fix null-pointer deref when freeing streams

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Message-ID: <f79f914e-2104-4706-9876-43d084aee1c3@linux.ibm.com>
Date: Tue, 8 Apr 2025 10:46:11 +0530
From: Sourabh Jain <sourabhjain@...ux.ibm.com>
To: Herbert Xu <herbert@...dor.apana.org.au>
Cc: Madhavan Srinivasan <maddy@...ux.ibm.com>,
        "David S. Miller" <davem@...emloft.net>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        linux-crypto@...r.kernel.org, lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] crypto: scomp - Fix null-pointer deref when freeing
 streams

Hello Herbert,


On 08/04/25 09:50, Herbert Xu wrote:
> On Mon, Apr 07, 2025 at 11:49:27PM +0530, Sourabh Jain wrote:
>> [   90.892796] NIP [c000000000845eb0] scomp_free_streams+0x6c/0xe8
>> [   90.892803] LR [c000000000845ee0] scomp_free_streams+0x9c/0xe8
> Looks like I never tested 842 which curiously does not have a
> self-test.  Please try this patch:
>
> ---8<---
> As the scomp streams are freed when an algorithm is unregistered,
> it is possible that the algorithm has never been used at all (e.g.,
> an algorithm that does not have a self-test).  So test whether the
> streams exist before freeing them.
>
> Reported-by: Sourabh Jain <sourabhjain@...ux.ibm.com>
> Fixes: 3d72ad46a23a ("crypto: acomp - Move stream management into scomp layer")
> Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
>
> diff --git a/crypto/scompress.c b/crypto/scompress.c
> index d435d4b24469..f67ce38d203d 100644
> --- a/crypto/scompress.c
> +++ b/crypto/scompress.c
> @@ -111,6 +111,9 @@ static void scomp_free_streams(struct scomp_alg *alg)
>   	struct crypto_acomp_stream __percpu *stream = alg->stream;
>   	int i;
>   
> +	if (!stream)
> +		return;
> +
>   	for_each_possible_cpu(i) {
>   		struct crypto_acomp_stream *ps = per_cpu_ptr(stream, i);
>   

The above fix resolves the reported issue.

Thanks for the fix.

Feel free to add:

Tested-by: Sourabh Jain <sourabhjain@...ux.ibm.com>

Thanks,
Sourabh Jain