In gfs2_rgrp_bh_get, there is an if statement on line 1191 to check
whether "rgd->rd_bits[0].bi_bh" is NULL.
When "rgd->rd_bits[0].bi_bh" is NULL, it is used on line 1216:
gfs2_rgrp_in(rgd, (rgd->rd_bits[0].bi_bh)->b_data);
and on line 1225:
gfs2_rgrp_ondisk2lvb(..., rgd->rd_bits[0].bi_bh->b_data);
and on line 1228:
if (!gfs2_rgrp_lvb_valid(rgd))
Note that in gfs2_rgrp_lvb_valid(rgd), there is a statement on line 1114:
struct gfs2_rgrp *str = (struct gfs2_rgrp
*)rgd->rd_bits[0].bi_bh->b_data;
Thus, possible null-pointer dereferences may occur.
These bugs are found by a static analysis tool STCheck written by us.
I do not know how to correctly fix these bugs, so I only report bugs.
Best wishes,
Jia-Ju Bai
Hi,
On 24/07/2019 09:50, Jia-Ju Bai wrote:
> In gfs2_rgrp_bh_get, there is an if statement on line 1191 to check
> whether "rgd->rd_bits[0].bi_bh" is NULL.
That is how we detect whether the rgrp has already been read in, so the
function is skipped in the case that we've already read in the rgrp.
> When "rgd->rd_bits[0].bi_bh" is NULL, it is used on line 1216:
> gfs2_rgrp_in(rgd, (rgd->rd_bits[0].bi_bh)->b_data);
No it isn't. See line 1196 where bi_bh is set, and where we also bail
out (line 1198) in case it has not been set.
> and on line 1225:
> gfs2_rgrp_ondisk2lvb(..., rgd->rd_bits[0].bi_bh->b_data);
> and on line 1228:
> if (!gfs2_rgrp_lvb_valid(rgd))
>
> Note that in gfs2_rgrp_lvb_valid(rgd), there is a statement on line 1114:
> struct gfs2_rgrp *str = (struct gfs2_rgrp
> *)rgd->rd_bits[0].bi_bh->b_data;
>
> Thus, possible null-pointer dereferences may occur.
>
> These bugs are found by a static analysis tool STCheck written by us.
> I do not know how to correctly fix these bugs, so I only report bugs.
>
>
> Best wishes,
> Jia-Ju Bai
>
So I'm not seeing how there can be a NULL deref in those later lines. I
think this is another false positive,
Steve.
Thanks for the reply :)
On 2019/7/24 17:04, Steven Whitehouse wrote:
> Hi,
>
> On 24/07/2019 09:50, Jia-Ju Bai wrote:
>> In gfs2_rgrp_bh_get, there is an if statement on line 1191 to check
>> whether "rgd->rd_bits[0].bi_bh" is NULL.
>
> That is how we detect whether the rgrp has already been read in, so
> the function is skipped in the case that we've already read in the rgrp.
>
>
>> When "rgd->rd_bits[0].bi_bh" is NULL, it is used on line 1216:
>> gfs2_rgrp_in(rgd, (rgd->rd_bits[0].bi_bh)->b_data);
>
> No it isn't. See line 1196 where bi_bh is set, and where we also bail
> out (line 1198) in case it has not been set.
>
I overlooked the operation on line 1196...
Thanks for the pointer, I am sorry for the false report...
Best wishes,
Jia-Ju Bai