Re: Re: PING: [PATCH] crypto: public_key: fix overflow during implicit conversion

From: zhenwei pi
Date: Wed Aug 18 2021 - 22:04:46 EST

On 8/18/21 8:33 PM, Jarkko Sakkinen wrote:
On Wed, 2021-08-18 at 16:33 +0800, zhenwei pi wrote:

Please, do not top-post.

You are lacking Herbert Xu:

$ scripts/ crypto/asymmetric_keys/public_key.c
David Howells <dhowells@xxxxxxxxxx> (maintainer:ASYMMETRIC KEYS)
Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> (maintainer:CRYPTO API)
"David S. Miller" <davem@xxxxxxxxxxxxx> (maintainer:CRYPTO API)
keyrings@xxxxxxxxxxxxxxx (open list:ASYMMETRIC KEYS)
linux-crypto@xxxxxxxxxxxxxxx (open list:CRYPTO API)
linux-kernel@xxxxxxxxxxxxxxx (open list)

On 8/10/21 2:39 PM, zhenwei pi wrote:
Hit kernel warning like this, it can be reproduced by verifying 256
bytes datafile by keyctl command.

WARNING: CPU: 5 PID: 344556 at crypto/rsa-pkcs1pad.c:540
Call Trace:
? software_key_query+0x12d/0x180
? keyctl_pkey_params_get+0xd6/0x130

'.digest_size(u8) = params->in_len(u32)' leads overflow of an u8

Where is this statement?

In function "static int asymmetric_key_verify_signature(struct kernel_pkey_params *params, const void *in, const void *in2)"

so use u32 instead of u8 of digest. And reorder struct
public_key_signature, it could save 8 bytes on a 64 bit machine.
What do you mean by "could"? Does it, or does it

After reordering struct public_key_signature, sizeof(struct public_key_signature) gets smaller than the original version.

Signed-off-by: zhenwei pi <pizhenwei@xxxxxxxxxxxxx>

Nit: "Firstname Lastname" (first letters capitalized)

include/crypto/public_key.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/crypto/public_key.h
index 47accec68cb0..f603325c0c30 100644
--- a/include/crypto/public_key.h
+++ b/include/crypto/public_key.h
@@ -38,9 +38,9 @@ extern void public_key_free(struct public_key
struct public_key_signature {
struct asymmetric_key_id *auth_ids[2];
u8 *s; /* Signature */
- u32 s_size; /* Number of bytes in signature */
u8 *digest;
- u8 digest_size; /* Number of bytes in digest */
+ u32 s_size; /* Number of bytes in signature */
+ u32 digest_size; /* Number of bytes in digest */
const char *pkey_algo;
const char *hash_algo;
const char *encoding;


zhenwei pi