Re: [PATCH] crypto: scompress - fix req->dst buffer overflow

[Chengming Zhou <chengming.zhou@linux.dev>]

On 2023/12/27 17:26, Herbert Xu wrote:
> On Wed, Dec 27, 2023 at 06:50:43AM +0000, chengming.zhou@linux.dev wrote:
>> From: Chengming Zhou <zhouchengming@bytedance.com>
>>
>> The req->dst buffer size should be checked before copying from the
>> scomp_scratch->dst to avoid req->dst buffer overflow problem.
>>
>> Fixes: 1ab53a77b772 ("crypto: acomp - add driver-side scomp interface")
>> Reported-by: syzbot+3eff5e51bf1db122a16e@syzkaller.appspotmail.com
>> Closes: https://lore.kernel.org/all/0000000000000b05cd060d6b5511@google.com/
>> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
>> ---
>>  crypto/scompress.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/crypto/scompress.c b/crypto/scompress.c
>> index 442a82c9de7d..e654a120ae5a 100644
>> --- a/crypto/scompress.c
>> +++ b/crypto/scompress.c
>> @@ -117,6 +117,7 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
>>  	struct crypto_scomp *scomp = *tfm_ctx;
>>  	void **ctx = acomp_request_ctx(req);
>>  	struct scomp_scratch *scratch;
>> +	unsigned int dlen;
>>  	int ret;
>>  
>>  	if (!req->src || !req->slen || req->slen > SCOMP_SCRATCH_SIZE)
>> @@ -128,6 +129,8 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
>>  	if (!req->dlen || req->dlen > SCOMP_SCRATCH_SIZE)
>>  		req->dlen = SCOMP_SCRATCH_SIZE;
>>  
>> +	dlen = req->dlen;
>> +
>>  	scratch = raw_cpu_ptr(&scomp_scratch);
>>  	spin_lock(&scratch->lock);
>>  
>> @@ -145,6 +148,9 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
>>  				ret = -ENOMEM;
>>  				goto out;
>>  			}
>> +		} else if (req->dlen > dlen) {
>> +			ret = -ENOMEM;
>> +			goto out;
> 
> I think ENOMEM is ambiguous, perhaps ENOSPC?

Right, ENOSPC is better. Should I send a v2?

Thanks.