On Thu, Dec 10, 2015 at 11:13:38AM -0500, Mike Marciniszyn wrote:
> From: Easwar Hariharan <easwar.hariharan@xxxxxxxxx>
>
> A code inspection pointed out that kmalloc_array may return NULL and
> memset doesn't check the input pointer for NULL, resulting in a possible
> NULL dereference. This patch fixes this.
>
> Reviewed-by: Mike Marciniszyn <mike.marciniszyn@xxxxxxxxx>
> Signed-off-by: Easwar Hariharan <easwar.hariharan@xxxxxxxxx>
> ---
> drivers/staging/rdma/hfi1/chip.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/staging/rdma/hfi1/chip.c b/drivers/staging/rdma/hfi1/chip.c
> index dc69159..49d49b2 100644
> --- a/drivers/staging/rdma/hfi1/chip.c
> +++ b/drivers/staging/rdma/hfi1/chip.c
> @@ -10129,6 +10129,8 @@ static void init_qos(struct hfi1_devdata *dd, u32 first_ctxt)
> if (num_vls * qpns_per_vl > dd->chip_rcv_contexts)
> goto bail;
> rsmmap = kmalloc_array(NUM_MAP_REGS, sizeof(u64), GFP_KERNEL);
> + if (!rsmmap)
> + goto bail;
> memset(rsmmap, rxcontext, NUM_MAP_REGS * sizeof(u64));
> /* init the local copy of the table */
> for (i = 0, ctxt = first_ctxt; i < num_vls; i++) {
>
> --
Based on this report a generalization of unchecked use turned up one more
case in the current kernel (patch sent). Probably the when block needs
some cleanup, but findings like this definitely are a case for coccinelle
scanners.
<snip>
/// check for missing NULL check before use
//
// missing check in:
// ./drivers/staging/rdma/hfi1/chip.c:10131 unchecked allocation
// in -next-20151214
// reported-by Mike Marciniszyn <mike.marciniszyn@xxxxxxxxx>
//
// after generalization this also found:
// ./drivers/clk/shmobile/clk-div6.c:197 unchecked allocation
virtual context
virtual org
virtual report
@badmemset@
expression mem;
position p;
statement S;
@@
<+...
*mem = kmalloc_array@p(...);
... when != if (!mem || ...) S
when != if (... && !mem) S
when != if (mem == NULL || ...) S
when != if (... && mem == NULL) S
when != if (unlikely(mem == NULL)) S
when != if (unlikely(!mem)) S
when != if (likely(!mem)) S
when != if (likely(mem == NULL)) S
return;
...+>
@script:python@
p << badmemset.p;
@@
print "%s:%s unchecked allocation" % (p[0].file,p[0].line)
<snip>
thx!
hofrat
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