2018-11-21 09:21:44

by Wen Yang

Subject: [PATCH 2/4] soc/fsl/qe: fix potential NULL pointer dereference in ucc_of_parse_tdm

This patch fixes a possible null pointer dereference in
ucc_of_parse_tdm, detected by the semantic patch
deref_null.cocci, with the following warning:

./drivers/soc/fsl/qe/qe_tdm.c:177:21-24: ERROR: pdev is NULL but dereferenced.

The following code has potential null pointer references:
pdev = of_find_device_by_node(np2);
if (!pdev) {
ret = -EINVAL;
pr_err("%pOFn: failed to lookup pdev\n", np2);
of_node_put(np2);
goto err_miss_siram_property;
}
...
err_miss_siram_property:
devm_iounmap(&pdev->dev, utdm->si_regs);

Signed-off-by: Wen Yang <[email protected]>
Reviewed-by: Tan Hu <[email protected]>
CC: Julia Lawall <[email protected]>
---
drivers/soc/fsl/qe/qe_tdm.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/fsl/qe/qe_tdm.c b/drivers/soc/fsl/qe/qe_tdm.c
index f78c346..166378b 100644
--- a/drivers/soc/fsl/qe/qe_tdm.c
+++ b/drivers/soc/fsl/qe/qe_tdm.c
@@ -174,7 +174,8 @@ int ucc_of_parse_tdm(struct device_node *np, struct ucc_tdm *utdm,
return ret;

err_miss_siram_property:
- devm_iounmap(&pdev->dev, utdm->si_regs);
+ if (pdev)
+ devm_iounmap(&pdev->dev, utdm->si_regs);
return ret;
}
EXPORT_SYMBOL(ucc_of_parse_tdm);
--
2.9.5

2018-11-21 11:40:03

by Christophe Leroy

Subject: Re: [PATCH 2/4] soc/fsl/qe: fix potential NULL pointer dereference in ucc_of_parse_tdm

Le 21/11/2018 à 08:41, Wen Yang a écrit :
> This patch fixes a possible null pointer dereference in
> ucc_of_parse_tdm, detected by the semantic patch
> deref_null.cocci, with the following warning:
>
> ./drivers/soc/fsl/qe/qe_tdm.c:177:21-24: ERROR: pdev is NULL but dereferenced.
>
> The following code has potential null pointer references:
> pdev = of_find_device_by_node(np2);
> if (!pdev) {
> ret = -EINVAL;
> pr_err("%pOFn: failed to lookup pdev\n", np2);
> of_node_put(np2);
> goto err_miss_siram_property;
> }
> ...
> err_miss_siram_property:
> devm_iounmap(&pdev->dev, utdm->si_regs);
>
> Signed-off-by: Wen Yang <[email protected]>
> Reviewed-by: Tan Hu <[email protected]>
> CC: Julia Lawall <[email protected]>
> ---
> drivers/soc/fsl/qe/qe_tdm.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/soc/fsl/qe/qe_tdm.c b/drivers/soc/fsl/qe/qe_tdm.c
> index f78c346..166378b 100644
> --- a/drivers/soc/fsl/qe/qe_tdm.c
> +++ b/drivers/soc/fsl/qe/qe_tdm.c
> @@ -174,7 +174,8 @@ int ucc_of_parse_tdm(struct device_node *np, struct ucc_tdm *utdm,
> return ret;
>
> err_miss_siram_property:
> - devm_iounmap(&pdev->dev, utdm->si_regs);
> + if (pdev)
> + devm_iounmap(&pdev->dev, utdm->si_regs);

You are just hiding the issue, not fixing it.

The problem is that pdev gets modified, so in any case that
devm_iounmap() will fail even when the new pdev is valid, because the
iomap was done with a different pdev.

Christophe



> return ret;
> }
> EXPORT_SYMBOL(ucc_of_parse_tdm);
>