Re: [PATCH] crypto: caam - reject overlong RSA CRT parameters

["Jérémy Jean" <jeremy.jean@oss.cyber.gouv.fr>]

On 2026-08-26 02:21, Herbert Xu wrote:
> On Mon, Aug 10, 2026 at 03:40:24PM +0000, Jérémy Jean wrote:
>> caam_read_rsa_crt() right-aligns dP, dQ, and qInv in buffers sized
>> from the corresponding prime. rsa_parse_priv_key() only bounds these
>> integers against n, so a malformed key can provide, for example, a
>> two-byte dP with a one-byte p. dstlen - nbytes then underflows and
>> memcpy() writes outside the allocation during set_priv_key(). KASAN
>> reports a slab-out-of-bounds write in caam_read_rsa_crt().
>> 
>> Reject empty or overlong CRT parameters after stripping leading zeros.
>> qInv is consumed by CAAM as a p-sized value, so size it from p rather
>> than q to match the DMA mapping in set_rsa_priv_f3_pdb(). Let the
>> top-level key cleanup handle partial form-3 allocations and return the
>> specific error to the caller.
>> 
>> Also test nbytes before dereferencing it while stripping zeros, so an
>> all-zero integer does not read one byte beyond its input.
>> 
>> Fixes: 4a651b122adb ("crypto: caam - add support for RSA key form 3")
>> Cc: stable@vger.kernel.org
>> Assisted-by: Codex:gpt-5
>> Signed-off-by: Jérémy Jean <Jeremy.Jean@oss.cyber.gouv.fr>
>> ---
>>  drivers/crypto/caam/caampkc.c | 69 
>> +++++++++++++++--------------------
>>  1 file changed, 30 insertions(+), 39 deletions(-)
> 
> Is this driver still maintained? If not let's just remove it.
> 
> Thanks,

Hello,

I don't know for sure, but it is still getting fixed, e.g.,
https://lore.kernel.org/all/FF2F0DC4D3930E6A+20260923101457.204629-1-zhaojinming@uniontech.com/

Regards,
Jérémy