[PATCH] ima/evm: Fix potential memory leak in ima_init_crypto()

[PATCH] ima/evm: Fix potential memory leak in ima_init_crypto()

[Jianglei Nie]

ima_init_crypto() allocates a memory chunk for "ima_algo_array" with
kcalloc(). When some errors occur, the function jumps to "out_array"
and releases the "ima_algo_array[i].tfm". But "ima_algo_array" is
not released, which will lead to a memory leak.

We can release the ima_algo_array with kfree() when some errors occur
to fix the memory leak.

Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
---
 security/integrity/ima/ima_crypto.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index a7206cc1d7d1..64499056648a 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -205,6 +205,7 @@ int __init ima_init_crypto(void)
 
 		crypto_free_shash(ima_algo_array[i].tfm);
 	}
+	kfree(ima_algo_array);
 out:
 	crypto_free_shash(ima_shash_tfm);
 	return rc;
-- 
2.25.1

Re: [PATCH] ima/evm: Fix potential memory leak in ima_init_crypto()

[Mimi Zohar]

Hi Jianglei,

Thank you for the patch.

On Mon, 2022-07-04 at 08:59 +0800, Jianglei Nie wrote:
> ima_init_crypto() allocates a memory chunk for "ima_algo_array" with
> kcalloc(). When some errors occur, the function jumps to "out_array"
> and releases the "ima_algo_array[i].tfm". But "ima_algo_array" is
> not released, which will lead to a memory leak.

There's too much low level code details in the above paragraph.  The
patch description should be written from a higher level perspective. 
Refer to the original commit 6d94809af6b0 ("ima: Allocate and
initialize tfm for each PCR bank") for an example.
> 
> We can release the ima_algo_array with kfree() when some errors occur
> to fix the memory leak.

Please re-word the above sentence in the imperative mode.  Refer to
Documentation/process/submitting-patches.rst for an example.

thanks,

Mimi
> 
> Signed-off-by: Jianglei Nie <niejianglei2021@163.com>

[PATCH] ima/evm: Fix potential memory leak in ima_init_crypto()

[Jianglei Nie]

This patch adds the missing kfree() for ima_algo_array allocated by
kcalloc() to avoid potential memory leak.

Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
---
 security/integrity/ima/ima_crypto.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index a7206cc1d7d1..64499056648a 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -205,6 +205,7 @@ int __init ima_init_crypto(void)
 
 		crypto_free_shash(ima_algo_array[i].tfm);
 	}
+	kfree(ima_algo_array);
 out:
 	crypto_free_shash(ima_shash_tfm);
 	return rc;
-- 
2.25.1

Re: [PATCH] ima/evm: Fix potential memory leak in ima_init_crypto()

[Mimi Zohar]

On Mon, 2022-07-11 at 15:22 +0800, Jianglei Nie wrote:
> This patch adds the missing kfree() for ima_algo_array allocated by
> kcalloc() to avoid potential memory leak.

Missing is the reason that ima_algo_array is being freed.

Perhaps something like, 
"On failure to allocate the SHA1 tfm, IMA fails to initialize and exits
without freeing the ima_algo_array.   Add the missing kfree() for
ima_algo_array to avoid the potential memory leak."

thanks,

Mimi