Re: [PATCH] mm: hugetlb: checking for IS_ERR() instead of NULL

[Dan Carpenter <dan.carpenter@oracle.com>]

On Wed, Jun 02, 2021 at 05:47:52PM +0300, Dan Carpenter wrote:
> On Tue, Jun 01, 2021 at 11:50:06PM +0300, Dan Carpenter wrote:
> > On Tue, Jun 01, 2021 at 10:51:23PM +0300, Dan Carpenter wrote:
> > > The other thing which might be interesting is if you pass a NULL
> > > to IS_ERR() and then dereference the NULL then print a warning about
> > > that.  This has a lot of overlaps with some of my existing checks, but
> > > it's still a new idea so it belongs in a separate check.  It's fine and
> > > good even if one bug triggers a lot of different warnings.  I'll write
> > > that, hang on, brb.
> > 
> > 100% untested.  :)  I'll test it tonight.
> > 
> 

I also added a check for:

	if (is_impossible_path())
		return;

to silence some of the false positives.  But the results are all still
false positives.  They're "high quality" false positives, because often
the code looks buggy.  I think that someone went through and fixed all
the real bugs with this.

I reported the snd_media_device_create() bug and sent a fix for the
nfs_init_server() but the rest, I'm just going to leave.

sound/usb/media.c:287 snd_media_device_create() error: potential NULL/IS_ERR bug 'mdev'
mm/mempolicy.c:1293 do_mbind() error: potential NULL/IS_ERR bug 'new'
fs/nfs/client.c:701 nfs_init_server() error: potential NULL/IS_ERR bug 'clp'
fs/afs/server.c:652 afs_update_server_record() error: potential NULL/IS_ERR bug 'alist'
fs/afs/volume.c:322 afs_update_volume_status() error: potential NULL/IS_ERR bug 'vldb'
fs/ubifs/lpt_commit.c:583 next_pnode_to_dirty() error: potential NULL/IS_ERR bug 'nnode'
fs/ubifs/lpt_commit.c:583 next_pnode_to_dirty() error: potential NULL/IS_ERR bug 'nnode'
fs/ntfs/attrib.c:2188 ntfs_attr_extend_allocation() error: potential NULL/IS_ERR bug 'rl'
fs/ext4/namei.c:2375 ext4_add_entry() error: potential NULL/IS_ERR bug 'bh'
drivers/pinctrl/renesas/core.c:1144 sh_pfc_probe() error: potential NULL/IS_ERR bug 'info'
drivers/mfd/ene-kb3930.c:165 kb3930_probe() error: potential NULL/IS_ERR bug 'ddata->off_gpios'
drivers/mtd/ubi/attach.c:409 add_volume() error: potential NULL/IS_ERR bug 'av'
drivers/mtd/ubi/fastmap.c:185 add_vol() error: potential NULL/IS_ERR bug 'av'
drivers/gpu/drm/nouveau/nvkm/engine/nvdec/base.c:57 nvkm_nvdec_new_() error: potential NULL/IS_ERR bug 'fwif'
drivers/gpu/drm/nouveau/nvkm/engine/sec2/base.c:104 nvkm_sec2_new_() error: potential NULL/IS_ERR bug 'fwif'
drivers/gpu/drm/nouveau/nvkm/engine/gr/gf100.c:2108 gf100_gr_new_() error: potential NULL/IS_ERR bug 'fwif'
drivers/gpu/drm/nouveau/nvkm/engine/nvenc/base.c:59 nvkm_nvenc_new_() error: potential NULL/IS_ERR bug 'fwif'
drivers/gpu/drm/nouveau/nvkm/subdev/pmu/base.c:181 nvkm_pmu_ctor() error: potential NULL/IS_ERR bug 'fwif'
drivers/gpu/drm/nouveau/nvkm/subdev/gsp/base.c:56 nvkm_gsp_new_() error: potential NULL/IS_ERR bug 'fwif'
drivers/gpu/drm/nouveau/nvkm/subdev/acr/base.c:430 nvkm_acr_new_() error: potential NULL/IS_ERR bug 'fwif'
drivers/clk/clk.c:417 clk_core_get() error: potential NULL/IS_ERR bug 'hw'
drivers/platform/chrome/cros_ec_chardev.c:225 cros_ec_chardev_read() error: potential NULL/IS_ERR bug 'event'
net/xfrm/xfrm_policy.c:2785 xfrm_policy_queue_process() error: potential NULL/IS_ERR bug 'dst'
net/xfrm/xfrm_interface.c:282 xfrmi_xmit2() error: potential NULL/IS_ERR bug 'dst'
net/ipv6/netfilter/nf_reject_ipv6.c:327 nf_send_reset6() error: potential NULL/IS_ERR bug 'dst'
net/ipv6/ip6_tunnel.c:1161 ip6_tnl_xmit() error: potential NULL/IS_ERR bug 'dst'
net/ipv6/ndisc.c:505 ndisc_send_skb() error: potential NULL/IS_ERR bug 'dst'
security/selinux/hooks.c:3157 selinux_inode_follow_link() error: potential NULL/IS_ERR bug 'isec'
security/selinux/hooks.c:3212 selinux_inode_permission() error: potential NULL/IS_ERR bug 'isec'

regards,
dan carpenter