Re: [PATCH 1/2] ima: Free IMA measurement buffer on error

2021-02-03 Thread Lakshmi Ramasubramanian 

On 1/22/21 2:30 PM, Thiago Jung Bauermann wrote:


Hi Lakshmi,

Lakshmi Ramasubramanian  writes:


IMA allocates kernel virtual memory to carry forward the measurement
list, from the current kernel to the next kernel on kexec system call,
in ima_add_kexec_buffer() function.  In error code paths this memory
is not freed resulting in memory leak.

Free the memory allocated for the IMA measurement list in
the error code paths in ima_add_kexec_buffer() function.

Signed-off-by: Lakshmi Ramasubramanian 
Suggested-by: Tyler Hicks 
Fixes: 7b8589cc29e7 ("ima: on soft reboot, save the measurement list")
---
  security/integrity/ima/ima_kexec.c | 2 ++
  1 file changed, 2 insertions(+)

diff --git a/security/integrity/ima/ima_kexec.c 
b/security/integrity/ima/ima_kexec.c
index 121de3e04af2..212145008a01 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -119,12 +119,14 @@ void ima_add_kexec_buffer(struct kimage *image)
ret = kexec_add_buffer();
if (ret) {
pr_err("Error passing over kexec measurement buffer.\n");
+   vfree(kexec_buffer);
return;
}


This is a good catch.


Thanks.



  
  	ret = arch_ima_add_kexec_buffer(image, kbuf.mem, kexec_segment_size);

if (ret) {
pr_err("Error passing over kexec measurement buffer.\n");
+   vfree(kexec_buffer);
return;
}


But this would cause problems, because the buffer is still there in the
kimage and would cause kimage_load_segment() to access invalid memory.

There's no function to undo a kexec_add_buffer() to avoid this problem,
so I'd suggest just accepting the leak in this case. Fortunately, the
current implementations of arch_ima_add_kexec_buffer() are very simple
and cannot fail, so this is a theoretical problem.



Agreed. I'll post a new patch with the above change removed.

thanks,
 -lakshmi

Re: [PATCH 1/2] ima: Free IMA measurement buffer on error

2021-01-22 Thread Thiago Jung Bauermann 


Hi Lakshmi,

Lakshmi Ramasubramanian  writes:

> IMA allocates kernel virtual memory to carry forward the measurement
> list, from the current kernel to the next kernel on kexec system call,
> in ima_add_kexec_buffer() function.  In error code paths this memory
> is not freed resulting in memory leak.
>
> Free the memory allocated for the IMA measurement list in
> the error code paths in ima_add_kexec_buffer() function.
>
> Signed-off-by: Lakshmi Ramasubramanian 
> Suggested-by: Tyler Hicks 
> Fixes: 7b8589cc29e7 ("ima: on soft reboot, save the measurement list")
> ---
>  security/integrity/ima/ima_kexec.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/security/integrity/ima/ima_kexec.c 
> b/security/integrity/ima/ima_kexec.c
> index 121de3e04af2..212145008a01 100644
> --- a/security/integrity/ima/ima_kexec.c
> +++ b/security/integrity/ima/ima_kexec.c
> @@ -119,12 +119,14 @@ void ima_add_kexec_buffer(struct kimage *image)
>   ret = kexec_add_buffer();
>   if (ret) {
>   pr_err("Error passing over kexec measurement buffer.\n");
> + vfree(kexec_buffer);
>   return;
>   }

This is a good catch.

>  
>   ret = arch_ima_add_kexec_buffer(image, kbuf.mem, kexec_segment_size);
>   if (ret) {
>   pr_err("Error passing over kexec measurement buffer.\n");
> + vfree(kexec_buffer);
>   return;
>   }

But this would cause problems, because the buffer is still there in the
kimage and would cause kimage_load_segment() to access invalid memory.

There's no function to undo a kexec_add_buffer() to avoid this problem,
so I'd suggest just accepting the leak in this case. Fortunately, the
current implementations of arch_ima_add_kexec_buffer() are very simple
and cannot fail, so this is a theoretical problem.

-- 
Thiago Jung Bauermann
IBM Linux Technology Center

Re: [PATCH 1/2] ima: Free IMA measurement buffer on error

2021-01-21 Thread Tyler Hicks 
On 2021-01-21 09:30:02, Lakshmi Ramasubramanian wrote:
> IMA allocates kernel virtual memory to carry forward the measurement
> list, from the current kernel to the next kernel on kexec system call,
> in ima_add_kexec_buffer() function.  In error code paths this memory
> is not freed resulting in memory leak.
> 
> Free the memory allocated for the IMA measurement list in
> the error code paths in ima_add_kexec_buffer() function.
> 
> Signed-off-by: Lakshmi Ramasubramanian 
> Suggested-by: Tyler Hicks 
> Fixes: 7b8589cc29e7 ("ima: on soft reboot, save the measurement list")

Reviewed-by: Tyler Hicks 

Tyler

> ---
>  security/integrity/ima/ima_kexec.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/security/integrity/ima/ima_kexec.c 
> b/security/integrity/ima/ima_kexec.c
> index 121de3e04af2..212145008a01 100644
> --- a/security/integrity/ima/ima_kexec.c
> +++ b/security/integrity/ima/ima_kexec.c
> @@ -119,12 +119,14 @@ void ima_add_kexec_buffer(struct kimage *image)
>   ret = kexec_add_buffer();
>   if (ret) {
>   pr_err("Error passing over kexec measurement buffer.\n");
> + vfree(kexec_buffer);
>   return;
>   }
>  
>   ret = arch_ima_add_kexec_buffer(image, kbuf.mem, kexec_segment_size);
>   if (ret) {
>   pr_err("Error passing over kexec measurement buffer.\n");
> + vfree(kexec_buffer);
>   return;
>   }
>  
> -- 
> 2.30.0
>

[PATCH 1/2] ima: Free IMA measurement buffer on error

2021-01-21 Thread Lakshmi Ramasubramanian 
IMA allocates kernel virtual memory to carry forward the measurement
list, from the current kernel to the next kernel on kexec system call,
in ima_add_kexec_buffer() function.  In error code paths this memory
is not freed resulting in memory leak.

Free the memory allocated for the IMA measurement list in
the error code paths in ima_add_kexec_buffer() function.

Signed-off-by: Lakshmi Ramasubramanian 
Suggested-by: Tyler Hicks 
Fixes: 7b8589cc29e7 ("ima: on soft reboot, save the measurement list")
---
 security/integrity/ima/ima_kexec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/security/integrity/ima/ima_kexec.c 
b/security/integrity/ima/ima_kexec.c
index 121de3e04af2..212145008a01 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -119,12 +119,14 @@ void ima_add_kexec_buffer(struct kimage *image)
ret = kexec_add_buffer();
if (ret) {
pr_err("Error passing over kexec measurement buffer.\n");
+   vfree(kexec_buffer);
return;
}
 
ret = arch_ima_add_kexec_buffer(image, kbuf.mem, kexec_segment_size);
if (ret) {
pr_err("Error passing over kexec measurement buffer.\n");
+   vfree(kexec_buffer);
return;
}
 
-- 
2.30.0