[PATCH] bsps/shared/ofw: Fix coverity reported defects

[Christian MAUDERER]

Hello Niteesh,

Am 29.01.21 um 07:33 schrieb Niteesh G. S.:
> Hello,
> 
> https://lists.rtems.org/pipermail/devel/2021-January/064115.html 
> <https://lists.rtems.org/pipermail/devel/2021-January/064115.html>
> I have fixed defects reported in the above thread except
> CID 1472595, 1472597 (ARRAY_VS_SINGLETON)
> Along with the buffer we also take the size of the buffer this makes
> sure that we don't read more than the buffer capacity.
> But coverity reports this as an defect how can I fix this?

Thanks for taking a look at these. Regarding the CID 1472595:

What Coverity doesn't like is the following:

You create a variable (phandle_t ref). You then pass the pointer of the 
variable to the rtems_ofw_get_enc_prop in the pcell_t *buf parameter. 
And rtems_ofw_get_enc_prop uses a buf[i] which might could be more than 
0 if you ask Coverity. Coverity is most likely not intelligent enough to 
understand the logic. I think it might be possible to suppress that 
message by creating the variable with

     phandle_t ref[1];

and adapting the following uses of that variable. But please double 
check, that the code is correct when you do something like that. What 
isn't mentioned in that defect: In rtems_ofw_get_enc_prop you pass the 
buf to rtems_ofw_get_prop which uses a strncpy in line 201 to fill the 
buffer. That is _very_ odd for an integer value and might lead to wrong 
results.

Best regards

Christian

> 
> Thanks,
> Niteesh.
> 
> On Fri, Jan 29, 2021 at 11:48 AM G S Niteesh Babu <niteesh.gs at gmail.com 
> <mailto:niteesh.gs at gmail.com>> wrote:
> 
>     Fixed use after free and null pointer dereference defects
> 
>     FIXES:
>     1) CID 1472601 (NULL_RETURNS)
>     2) CID 1472600 (USE_AFTER_FREE)
>     3) CID 1472599 (USE_AFTER_FREE)
>     4) CID 1472598 (USE_AFTER_FREE)
>     5) CID 1472596 (USE_AFTER_FREE)
>     ---
>       bsps/shared/ofw/ofw.c | 10 +++++-----
>       1 file changed, 5 insertions(+), 5 deletions(-)
> 
>     diff --git a/bsps/shared/ofw/ofw.c b/bsps/shared/ofw/ofw.c
>     index 82924b2600..fa94bfbf05 100644
>     --- a/bsps/shared/ofw/ofw.c
>     +++ b/bsps/shared/ofw/ofw.c
>     @@ -313,7 +313,7 @@ ssize_t rtems_ofw_get_prop_alloc(
>           }
> 
>           if (rtems_ofw_get_prop(node, propname, *buf, len) == -1) {
>     -      rtems_ofw_free(buf);
>     +      rtems_ofw_free(*buf);
>             *buf = NULL;
>             return -1;
>           }
>     @@ -344,7 +344,7 @@ ssize_t rtems_ofw_get_prop_alloc_multi(
>           }
> 
>           if (rtems_ofw_get_prop(node, propname, *buf, len) == -1) {
>     -      rtems_ofw_free(buf);
>     +      rtems_ofw_free(*buf);
>             *buf = NULL;
>             return -1;
>           }
>     @@ -373,7 +373,7 @@ ssize_t rtems_ofw_get_enc_prop_alloc(
>           }
> 
>           if (rtems_ofw_get_enc_prop(node, propname, *buf, len) == -1) {
>     -      rtems_ofw_free(buf);
>     +      rtems_ofw_free(*buf);
>             *buf = NULL;
>             return -1;
>           }
>     @@ -404,7 +404,7 @@ ssize_t rtems_ofw_get_enc_prop_alloc_multi(
>           }
> 
>           if (rtems_ofw_get_enc_prop(node, propname, *buf, len) == -1) {
>     -      rtems_ofw_free(buf);
>     +      rtems_ofw_free(*buf);
>             *buf = NULL;
>             return -1;
>           }
>     @@ -614,7 +614,7 @@ int rtems_ofw_get_reg(
>           offset = rtems_fdt_phandle_to_offset(parent);
>           ptr = fdt_getprop(fdtp, offset, "ranges", &len);
> 
>     -    if (len < 0) {
>     +    if (ptr == NULL) {
>             break;
>           }
> 
>     -- 
>     2.17.1
> 

-- 
--------------------------------------------
embedded brains GmbH
Herr Christian MAUDERER
Dornierstr. 4
82178 Puchheim
Germany
email: christian.mauderer at embedded-brains.de
phone: +49-89-18 94 741 - 18
fax:   +49-89-18 94 741 - 08

Registergericht: Amtsgericht München
Registernummer: HRB 157899
Vertretungsberechtigte Geschäftsführer: Peter Rasmussen, Thomas Dörfler
Unsere Datenschutzerklärung finden Sie hier:
https://embedded-brains.de/datenschutzerklaerung/