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libsepol: avoid unsigned integer overflow

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Unsigned integer overflow is well-defined and not undefined behavior.
It is commonly used for hashing or pseudo random number generation.
But it is still useful to enable undefined behavior sanitizer checks on
unsigned arithmetic to detect possible issues on counters or variables
with similar purpose or missed overflow checks on user input.

Use a spaceship operator like comparison instead of subtraction.

    policydb.c:851:24: runtime error: unsigned integer overflow: 801 - 929 cannot be represented in type 'unsigned int'

Follow-up of: 1537ea8412 ("libsepol: avoid unsigned integer overflow")

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
This commit is contained in:
Christian Göttsche 2021-07-06 19:36:29 +02:00 committed by Nicolas Iooss
parent 9af9169241
commit 44d56761be
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GPG key ID: C191415F340DAAA0
2 changed files with 7 additions and 5 deletions
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10
libsepol/src/policydb.c
View file

@ -817,11 +817,11 @@ static int filenametr_cmp(hashtab_t h __attribute__ ((unused)),
const filename_trans_key_t *ft2 = (const filename_trans_key_t *)k2;
int v;
v = (ft1->ttype > ft2->ttype) - (ft1->ttype < ft2->ttype);
v = spaceship_cmp(ft1->ttype, ft2->ttype);
if (v)
return v;
v = (ft1->tclass > ft2->tclass) - (ft1->tclass < ft2->tclass);
v = spaceship_cmp(ft1->tclass, ft2->tclass);
if (v)
return v;
@ -843,15 +843,15 @@ static int rangetr_cmp(hashtab_t h __attribute__ ((unused)),
const struct range_trans *key2 = (const struct range_trans *)k2;
int v;
v = key1->source_type - key2->source_type;
v = spaceship_cmp(key1->source_type, key2->source_type);
if (v)
return v;
v = key1->target_type - key2->target_type;
v = spaceship_cmp(key1->target_type, key2->target_type);
if (v)
return v;
v = key1->target_class - key2->target_class;
v = spaceship_cmp(key1->target_class, key2->target_class);
return v;
}

2
libsepol/src/private.h
View file

@ -47,6 +47,8 @@
#define is_saturated(x) (x == (typeof(x))-1)
#define zero_or_saturated(x) ((x == 0) || is_saturated(x))
#define spaceship_cmp(a, b) (((a) > (b)) - ((a) < (b)))
/* Policy compatibility information. */
struct policydb_compat_info {
unsigned int type;