[PATCH] interconnect: qcom: icc-rpm: Set the count member before accessing the flex array

[PATCH] interconnect: qcom: icc-rpm: Set the count member before accessing the flex array

[djakov]

From: Georgi Djakov <djakov@kernel.org>

The following UBSAN error is reported during boot on the db410c board on
a clang-19 build:

Internal error: UBSAN: array index out of bounds: 00000000f2005512 [#1] PREEMPT SMP
...
pc : qnoc_probe+0x5f8/0x5fc
...

The cause of the error is that the counter member was not set before
accessing the annotated flexible array member, but after that. Fix this
by initializing it earlier.

Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Closes: https://lore.kernel.org/r/CA+G9fYs+2mBz1y2dAzxkj9-oiBJ2Acm1Sf1h2YQ3VmBqj_VX2g@mail.gmail.com
Fixes: dd4904f3b924 ("interconnect: qcom: Annotate struct icc_onecell_data with __counted_by")
Signed-off-by: Georgi Djakov <djakov@kernel.org>
---
 drivers/interconnect/qcom/icc-rpm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/interconnect/qcom/icc-rpm.c b/drivers/interconnect/qcom/icc-rpm.c
index a8ed435f696c..ea1042d38128 100644
--- a/drivers/interconnect/qcom/icc-rpm.c
+++ b/drivers/interconnect/qcom/icc-rpm.c
@@ -503,6 +503,7 @@ int qnoc_probe(struct platform_device *pdev)
 			    GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
+	data->num_nodes = num_nodes;
 
 	qp->num_intf_clks = cd_num;
 	for (i = 0; i < cd_num; i++)
@@ -597,7 +598,6 @@ int qnoc_probe(struct platform_device *pdev)
 
 		data->nodes[i] = node;
 	}
-	data->num_nodes = num_nodes;
 
 	clk_bulk_disable_unprepare(qp->num_intf_clks, qp->intf_clks);
 

Re: [PATCH] interconnect: qcom: icc-rpm: Set the count member before accessing the flex array

[Nathan Chancellor]

On Wed, Dec 04, 2024 at 12:33:34AM +0200, djakov@kernel.org wrote:
> From: Georgi Djakov <djakov@kernel.org>
> 
> The following UBSAN error is reported during boot on the db410c board on
> a clang-19 build:
> 
> Internal error: UBSAN: array index out of bounds: 00000000f2005512 [#1] PREEMPT SMP
> ...
> pc : qnoc_probe+0x5f8/0x5fc
> ...

Really happy to see more coverage of real hardware with compilers that
support __counted_by() so that we can start getting these addressed,
thanks for this!

> The cause of the error is that the counter member was not set before
> accessing the annotated flexible array member, but after that. Fix this
> by initializing it earlier.
> 
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Closes: https://lore.kernel.org/r/CA+G9fYs+2mBz1y2dAzxkj9-oiBJ2Acm1Sf1h2YQ3VmBqj_VX2g@mail.gmail.com
> Fixes: dd4904f3b924 ("interconnect: qcom: Annotate struct icc_onecell_data with __counted_by")

Guess Kees missed one :)

> Signed-off-by: Georgi Djakov <djakov@kernel.org>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

This is exactly the thing that __builtin_counted_by_ref() is trying to
address, as these assignments happen right after the allocation:

https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#index-_005f_005fbuiltin_005fcounted_005fby_005fref

> ---
>  drivers/interconnect/qcom/icc-rpm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/interconnect/qcom/icc-rpm.c b/drivers/interconnect/qcom/icc-rpm.c
> index a8ed435f696c..ea1042d38128 100644
> --- a/drivers/interconnect/qcom/icc-rpm.c
> +++ b/drivers/interconnect/qcom/icc-rpm.c
> @@ -503,6 +503,7 @@ int qnoc_probe(struct platform_device *pdev)
>  			    GFP_KERNEL);
>  	if (!data)
>  		return -ENOMEM;
> +	data->num_nodes = num_nodes;
>  
>  	qp->num_intf_clks = cd_num;
>  	for (i = 0; i < cd_num; i++)
> @@ -597,7 +598,6 @@ int qnoc_probe(struct platform_device *pdev)
>  
>  		data->nodes[i] = node;
>  	}
> -	data->num_nodes = num_nodes;
>  
>  	clk_bulk_disable_unprepare(qp->num_intf_clks, qp->intf_clks);
>  

Re: [PATCH] interconnect: qcom: icc-rpm: Set the count member before accessing the flex array

[Dan Carpenter]

Hi Greg,

Could you pick up this commit for 6.12 and 6.6:

00a973e093e9 ("interconnect: qcom: icc-rpm: Set the count member before accessing the flex array")

It just silences a UBSan warning so it doesn't affect regular users, but
it helps in testing to silence those warnings.  It is a clean cherry-pick.

regards,
dan carpenter


On Wed, Dec 04, 2024 at 12:33:34AM +0200, djakov@kernel.org wrote:
> From: Georgi Djakov <djakov@kernel.org>
> 
> The following UBSAN error is reported during boot on the db410c board on
> a clang-19 build:
> 
> Internal error: UBSAN: array index out of bounds: 00000000f2005512 [#1] PREEMPT SMP
> ...
> pc : qnoc_probe+0x5f8/0x5fc
> ...
> 
> The cause of the error is that the counter member was not set before
> accessing the annotated flexible array member, but after that. Fix this
> by initializing it earlier.
> 
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Closes: https://lore.kernel.org/r/CA+G9fYs+2mBz1y2dAzxkj9-oiBJ2Acm1Sf1h2YQ3VmBqj_VX2g@mail.gmail.com
> Fixes: dd4904f3b924 ("interconnect: qcom: Annotate struct icc_onecell_data with __counted_by")
> Signed-off-by: Georgi Djakov <djakov@kernel.org>
> ---
>  drivers/interconnect/qcom/icc-rpm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/interconnect/qcom/icc-rpm.c b/drivers/interconnect/qcom/icc-rpm.c
> index a8ed435f696c..ea1042d38128 100644
> --- a/drivers/interconnect/qcom/icc-rpm.c
> +++ b/drivers/interconnect/qcom/icc-rpm.c
> @@ -503,6 +503,7 @@ int qnoc_probe(struct platform_device *pdev)
>  			    GFP_KERNEL);
>  	if (!data)
>  		return -ENOMEM;
> +	data->num_nodes = num_nodes;
>  
>  	qp->num_intf_clks = cd_num;
>  	for (i = 0; i < cd_num; i++)
> @@ -597,7 +598,6 @@ int qnoc_probe(struct platform_device *pdev)
>  
>  		data->nodes[i] = node;
>  	}
> -	data->num_nodes = num_nodes;
>  
>  	clk_bulk_disable_unprepare(qp->num_intf_clks, qp->intf_clks);
>