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SubjectRe: [PATCH] security:trusted_tpm2: Fix memory leak in tpm2_key_encode()
KEYS: trusted: Fix memory leak in tpm2_key_encode()

On Tue, Dec 21, 2021 at 04:54:04PM +0800, Jianglei Nie wrote:
> Line 36 (#1) allocates a memory chunk for scratch by kmalloc(), but
> it is never freed through the function, which will lead to a memory
> leak.
>
> We should kfree() scratch before the function returns (#2, #3 and #4).
>
> 31 static int tpm2_key_encode(struct trusted_key_payload *payload,
> 32 struct trusted_key_options *options,
> 33 u8 *src, u32 len)
> 34 {
> 36 u8 *scratch = kmalloc(SCRATCH_SIZE, GFP_KERNEL);
> // #1: kmalloc space
> 50 if (!scratch)
> 51 return -ENOMEM;
>
> 56 if (options->blobauth_len == 0) {
> 60 if (WARN(IS_ERR(w), "BUG: Boolean failed to encode"))
> 61 return PTR_ERR(w); // #2: missing kfree
> 63 }
>
> 71 if (WARN(work - scratch + pub_len + priv_len + 14 > SCRATCH_SIZE,
> 72 "BUG: scratch buffer is too small"))
> 73 return -EINVAL; // #3: missing kfree
>
> // #4: missing kfree: scratch is never used afterwards.
> 82 if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed"))
> 83 return PTR_ERR(work1);
>
> 85 return work1 - payload->blob;
> 86 }
>
> Signed-off-by: Jianglei Nie <niejianglei2021@163.com>

Please write a proper commit message and not just dump tool output. You
are completely lacking analysis of what the heck you are doing.

E.g. you could just:

"The internal buffer in tpm2_key_encode() is not freed, which leads to a
memory leak. Handle those cases with kfree()."

/Jarkko

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