https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113619
Bug ID: 113619
Summary: -Wanalyzer-tainted-divisor false positive seen in
Linux kernel's fs/ceph/ioctl.c
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: analyzer
Assignee: dmalcolm at gcc dot gnu.org
Reporter: dmalcolm at gcc dot gnu.org
Blocks: 106358
Target Milestone: ---
Reduced from false positive in Linux kernel's kernel's fs/ceph/ioctl.c:
__extension__ typedef unsigned long long __u64;
struct ceph_ioctl_layout
{
__u64 stripe_unit, object_size;
};
static long
__validate_layout(struct ceph_ioctl_layout* l)
{
if ((l->object_size & ~(~(((1UL) << 12) - 1))) ||
(l->stripe_unit & ~(~(((1UL) << 12) - 1))) ||
((unsigned)l->stripe_unit != 0 &&
((unsigned)l->object_size % (unsigned)l->stripe_unit)))
return -22;
return 0;
}
long
__attribute__((tainted_args))
ceph_ioctl_set_layout_policy(struct ceph_ioctl_layout l)
{
int err;
err = __validate_layout(&l);
if (err)
return err;
return err;
}
t.c: In function ‘__validate_layout’:
t.c:13:34: warning: use of attacker-controlled value ‘l.stripe_unit’ as divisor
without checking for zero [CWE-369] [-Wanalyzer-tainted-divisor]
13 | ((unsigned)l->object_size % (unsigned)l->stripe_unit)))
| ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
‘ceph_ioctl_set_layout_policy’: event 1
|
| 20 | ceph_ioctl_set_layout_policy(struct ceph_ioctl_layout l)
| | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | |
| | (1) function ‘ceph_ioctl_set_layout_policy’ marked with
‘__attribute__((tainted_args))’
|
+--> ‘ceph_ioctl_set_layout_policy’: events 2-3
|
| 20 | ceph_ioctl_set_layout_policy(struct ceph_ioctl_layout l)
| | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | |
| | (2) entry to ‘ceph_ioctl_set_layout_policy’
|......
| 23 | err = __validate_layout(&l);
| | ~~~~~~~~~~~~~~~~~~~~~
| | |
| | (3) calling ‘__validate_layout’ from
‘ceph_ioctl_set_layout_policy’
|
+--> ‘__validate_layout’: events 4-11
|
| 8 | __validate_layout(struct ceph_ioctl_layout* l)
| | ^~~~~~~~~~~~~~~~~
| | |
| | (4) entry to ‘__validate_layout’
| 9 | {
| 10 | if ((l->object_size & ~(~(((1UL) << 12) - 1))) ||
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | | |
| | (5) following ‘false’ branch... (7)
following ‘false’ branch...
| 11 | (l->stripe_unit & ~(~(((1UL) << 12) - 1))) ||
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | | |
| | (6) ...to here (9)
following ‘true’ branch...
| 12 | ((unsigned)l->stripe_unit != 0 &&
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | |
| | (8) ...to here
| 13 | ((unsigned)l->object_size %
(unsigned)l->stripe_unit)))
| |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | | |
| | (10) ...to here (11) use of
attacker-controlled value ‘l.stripe_unit’ as divisor without checking for zero
|
...whereas (unsigned)l->stripe_unit != 0 is checked at line 12.
Affects trunk: https://godbolt.org/z/3qfx6scT8
Might show up on earlier releases, but taint state machine required opt-in on
them.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106358
[Bug 106358] [meta-bug] tracker bug for building the Linux kernel with
-fanalyzer
