[PATCH] fpga: fix potential null pointer deref in fpga_mgr_test_img_load_sgt()

[PATCH] fpga: fix potential null pointer deref in fpga_mgr_test_img_load_sgt()

[Qasim Ijaz]

fpga_mgr_test_img_load_sgt() allocates memory for sgt using
kunit_kzalloc() however it does not check if the allocation failed. 
It then passes sgt to sg_alloc_table(), which passes it to
__sg_alloc_table(). This function calls memset() on sgt in an attempt to
zero it out. If the allocation fails then sgt will be NULL and the
memset will trigger a NULL pointer dereference.

Fix this by checking the allocation with KUNIT_ASSERT_NOT_ERR_OR_NULL().

Fixes: ccbc1c302115 ("fpga: add an initial KUnit suite for the FPGA Manager")
Cc: stable@vger.kernel.org
Signed-off-by: Qasim Ijaz <qasdev00@gmail.com>
---
 drivers/fpga/tests/fpga-mgr-test.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/fpga/tests/fpga-mgr-test.c b/drivers/fpga/tests/fpga-mgr-test.c
index 9cb37aefbac4..1902ebf5a298 100644
--- a/drivers/fpga/tests/fpga-mgr-test.c
+++ b/drivers/fpga/tests/fpga-mgr-test.c
@@ -263,6 +263,7 @@ static void fpga_mgr_test_img_load_sgt(struct kunit *test)
 	img_buf = init_test_buffer(test, IMAGE_SIZE);
 
 	sgt = kunit_kzalloc(test, sizeof(*sgt), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, sgt);
 	ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
 	KUNIT_ASSERT_EQ(test, ret, 0);
 	sg_init_one(sgt->sgl, img_buf, IMAGE_SIZE);
-- 
2.39.5

Re: [PATCH] fpga: fix potential null pointer deref in fpga_mgr_test_img_load_sgt()

[Markus Elfring]

…
> zero it out. If the allocation fails then sgt will be NULL and the
…
                                 failed?


Can a summary phrase like “Prevent null pointer dereference
in fpga_mgr_test_img_load_sgt()” be nicer?

Regards,
Markus

Re: [PATCH] fpga: fix potential null pointer deref in fpga_mgr_test_img_load_sgt()

[Greg KH]

On Wed, Mar 12, 2025 at 02:01:48PM +0100, Markus Elfring wrote:
> …
> > zero it out. If the allocation fails then sgt will be NULL and the
> …
>                                  failed?
> 
> 
> Can a summary phrase like “Prevent null pointer dereference
> in fpga_mgr_test_img_load_sgt()” be nicer?
> 
> Regards,
> Markus
> 

Hi,

This is the semi-friendly patch-bot of Greg Kroah-Hartman.

Markus, you seem to have sent a nonsensical or otherwise pointless
review comment to a patch submission on a Linux kernel developer mailing
list.  I strongly suggest that you not do this anymore.  Please do not
bother developers who are actively working to produce patches and
features with comments that, in the end, are a waste of time.

Patch submitter, please ignore Markus's suggestion; you do not need to
follow it at all.  The person/bot/AI that sent it is being ignored by
almost all Linux kernel maintainers for having a persistent pattern of
behavior of producing distracting and pointless commentary, and
inability to adapt to feedback.  Please feel free to also ignore emails
from them.

thanks,

greg k-h's patch email bot

Re: [PATCH] fpga: fix potential null pointer deref in fpga_mgr_test_img_load_sgt()

[Marco Pagani]

On 2025-03-12 00:45, Qasim Ijaz wrote:
> fpga_mgr_test_img_load_sgt() allocates memory for sgt using
> kunit_kzalloc() however it does not check if the allocation failed. 
> It then passes sgt to sg_alloc_table(), which passes it to
> __sg_alloc_table(). This function calls memset() on sgt in an attempt to
> zero it out. If the allocation fails then sgt will be NULL and the
> memset will trigger a NULL pointer dereference.
> 
> Fix this by checking the allocation with KUNIT_ASSERT_NOT_ERR_OR_NULL().
> 
> Fixes: ccbc1c302115 ("fpga: add an initial KUnit suite for the FPGA Manager")
> Cc: stable@vger.kernel.org
> Signed-off-by: Qasim Ijaz <qasdev00@gmail.com>

Reviewed-by: Marco Pagani <marco.pagani@linux.dev>

> ---
>  drivers/fpga/tests/fpga-mgr-test.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/fpga/tests/fpga-mgr-test.c b/drivers/fpga/tests/fpga-mgr-test.c
> index 9cb37aefbac4..1902ebf5a298 100644
> --- a/drivers/fpga/tests/fpga-mgr-test.c
> +++ b/drivers/fpga/tests/fpga-mgr-test.c
> @@ -263,6 +263,7 @@ static void fpga_mgr_test_img_load_sgt(struct kunit *test)
>  	img_buf = init_test_buffer(test, IMAGE_SIZE);
>  
>  	sgt = kunit_kzalloc(test, sizeof(*sgt), GFP_KERNEL);
> +	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, sgt);
>  	ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
>  	KUNIT_ASSERT_EQ(test, ret, 0);
>  	sg_init_one(sgt->sgl, img_buf, IMAGE_SIZE);

Thanks,
Marco