Re: smatch warnings in current upstream kernel

[Fengguang Wu <fengguang.wu@intel.com>]

On Tue, Sep 11, 2012 at 05:29:26PM +0300, Dan Carpenter wrote:
> On Tue, Sep 11, 2012 at 07:06:40PM +0800, Fengguang Wu wrote:
> > On Tue, Sep 11, 2012 at 01:51:27PM +0300, Dan Carpenter wrote:
> >
> > $SMATCH -p kernel "$@" > $SMATCH_OUT_ROOT/$PPID-$$-$RANDOM

FYI, the wrapper script is as simple as

SMATCH=/c/smatch/smatch
$SMATCH -p kernel "$@" > $SMATCH_OUT_ROOT/$PPID-$$-$RANDOM

> Some of the warnings you are getting seem to mean that you're not
> picking up the smatch_data/ directory.  For example some of the
> buffer overflow errors:
> 
> drivers/mtd/ubi/wl.c:336 prot_queue_add() warn: buffer overflow 'ubi->pq' 10 <= 10
> 
> What is happening in that function is that Smatch sees the:
> 	ubi_assert(pq_tail >= 0 && pq_tail < UBI_PROT_QUEUE_LEN);
> 
> and assumes that since there is a test for
> "pq_tail < UBI_PROT_QUEUE_LEN" then it must be possible for
> pq_tail = UBI_PROT_QUEUE_LEN.  There is a file called:
> smatch_data/kernel.ignored_macros which has ubi_assert() and it
> means to ignore everything that happens inside a ubi_assert().

Yes, I can see the data and function. Thank you very much for the tips!

> Normally Smatch looks for the data dir with the binary, but you can
> also specify a directory with --data=/path/to/smatch_data/.  Then

The directory layout here is

/c/smatch/                      # git tree 
/c/smatch/smatch                # binary
/c/smatch/smatch_data/          # kernel.* data

> you can test that it's working by doing a:
> 	kchecker drivers/mtd/ubi/wl.c
> to verify that the warning goes away.

Both of these two tests run well w/o the above warning:

/c/smatch/smatch_scripts/kchecker drivers/mtd/ubi/wl.c

make C=1 CHECK=/c/kernel-tests/smatchcheck drivers/mtd/ubi/wl.o

This is interesting. I'll try adding --data=/c/smatch/smatch_data and
check whether the end result becomes better.

Thanks,
Fengguang