Re: [dpdk-dev] [PATCH] librte_acl: fix undefined behavior

[Aaron Conole <aconole@redhat.com>]

"Ananyev, Konstantin" <konstantin.ananyev@intel.com> writes:

> Hi Aaron,
>
>> 
>> Left-shift of an integer constant is represented as 'int' type, but a left
>> shift of 1 by 31 bits in 'int' is undefined.  Use the U suffix to force
>> a representation as unsigned.
>> 
>> Caught while running with ubsan under gcc.
>> 
>> Fixes: dc276b5780c2 ("acl: new library")
>> Cc: Konstantin Ananyev <konstantin.ananyev@intel.com>
>> Signed-off-by: Aaron Conole <aconole@redhat.com>
>> ---
>> I could have changed the sizeof(bits_t) * 8 in the bitset.bits as well during
>> the cleanup, but chose not to to keep the change minimal.
>
> But it seems that you did change it in some places:
>  
>> -				1 << (n % (sizeof(bits_t) * 8));
>> +				1U << (n % (sizeof(bits_t) * CHAR_BIT));
>
> While in others kept unchanged:
>> -				(1 << (n % (sizeof(bits_t) * 8)))) {
>> +				(1U << (n % (sizeof(bits_t) * 8)))) {
>
> Was that intended?

Oops - nope.  I'll respin.

> Konstantin
>
>> 
>>  lib/librte_acl/acl_bld.c | 6 +++---
>>  lib/librte_acl/acl_gen.c | 4 ++--
>>  2 files changed, 5 insertions(+), 5 deletions(-)
>> 
>> diff --git a/lib/librte_acl/acl_bld.c b/lib/librte_acl/acl_bld.c
>> index b82191f42..9d27c0a5a 100644
>> --- a/lib/librte_acl/acl_bld.c
>> +++ b/lib/librte_acl/acl_bld.c
>> @@ -320,7 +320,7 @@ acl_add_ptr_range(struct acl_build_context *context,
>>  	for (n = 0; n < UINT8_MAX + 1; n++)
>>  		if (n >= low && n <= high)
>>  			bitset.bits[n / (sizeof(bits_t) * 8)] |=
>> -				1 << (n % (sizeof(bits_t) * 8));
>> +				1U << (n % (sizeof(bits_t) * CHAR_BIT));
>> 
>>  	return acl_add_ptr(context, root, node, &bitset);
>>  }
>> @@ -343,7 +343,7 @@ acl_gen_mask(struct rte_acl_bitset *bitset, uint32_t value, uint32_t mask)
>>  		if ((n & mask) == value) {
>>  			range++;
>>  			bitset->bits[n / (sizeof(bits_t) * 8)] |=
>> -				1 << (n % (sizeof(bits_t) * 8));
>> +				1U << (n % (sizeof(bits_t) * CHAR_BIT));
>>  		}
>>  	}
>>  	return range;
>> @@ -972,7 +972,7 @@ build_trie(struct acl_build_context *context, struct rte_acl_build_rule *head,
>>  				sizeof(*end->mrt));
>> 
>>  		for (m = context->cfg.num_categories; 0 != m--; ) {
>> -			if (rule->f->data.category_mask & (1 << m)) {
>> +			if (rule->f->data.category_mask & (1U << m)) {
>>  				end->mrt->results[m] = rule->f->data.userdata;
>>  				end->mrt->priority[m] = rule->f->data.priority;
>>  			} else {
>> diff --git a/lib/librte_acl/acl_gen.c b/lib/librte_acl/acl_gen.c
>> index 35a0140b4..81dec3aa6 100644
>> --- a/lib/librte_acl/acl_gen.c
>> +++ b/lib/librte_acl/acl_gen.c
>> @@ -133,7 +133,7 @@ acl_node_fill_dfa(const struct rte_acl_node *node,
>>  		for (n = 0; n < RTE_ACL_DFA_SIZE; n++) {
>> 
>>  			if (bits->bits[n / (sizeof(bits_t) * CHAR_BIT)] &
>> -				(1 << (n % (sizeof(bits_t) * CHAR_BIT)))) {
>> +				(1U << (n % (sizeof(bits_t) * CHAR_BIT)))) {
>> 
>>  				dfa[n] = resolved ? child->node_index : x;
>>  				ranges += (last_bit == 0);
>> @@ -175,7 +175,7 @@ acl_count_sequential_groups(struct rte_acl_bitset *bits, int zero_one)
>>  	}
>>  	for (n = 0; n < QRANGE_MIN; n++) {
>>  		if (bits->bits[n / (sizeof(bits_t) * 8)] &
>> -				(1 << (n % (sizeof(bits_t) * 8)))) {
>> +				(1U << (n % (sizeof(bits_t) * 8)))) {
>>  			if (zero_one == 1 && last_bit != 1)
>>  				ranges++;
>>  			last_bit = 1;
>> --
>
>
>
>> 2.21.0