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[05/11] locate: Fix UB on memcpy call

Message ID 20250507142110.3452012-6-adhemerval.zanella@linaro.org
State New
Headers show
Series Add initial support for --enable-ubsan | expand

Commit Message

Adhemerval Zanella May 7, 2025, 2:17 p.m. UTC 
The ubsan triggers:

UBSAN: Undefined behaviour in programs/charmap.c:908:2 null pointer passed as argument 2, nonnull attribute declared at unknown:0:0

This is not an isseu since size is always '0' in this case.
---
 locale/programs/charmap.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Collin Funk May 8, 2025, 3 a.m. UTC | #1 
Adhemerval Zanella <adhemerval.zanella@linaro.org> writes:

> The ubsan triggers:
>
> UBSAN: Undefined behaviour in programs/charmap.c:908:2 null pointer passed as argument 2, nonnull attribute declared at unknown:0:0
>
> This is not an isseu since size is always '0' in this case.

s/isseu/issue :)

> -
> -      memcpy (new_rules, result->width_rules,
> -	      result->nwidth_rules_max * sizeof (struct width_rule));
> +      if (result->width_rules != NULL)
> +	memcpy (new_rules, result->width_rules,
> +		result->nwidth_rules_max * sizeof (struct width_rule));
[...]

This should be well defined in the future as long as the size is always
zero [1].

But I guess since it is still undefined, your change is correct...

Collin

[1] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3322.pdf
diff mbox series

Patch

diff --git a/locale/programs/charmap.c b/locale/programs/charmap.c
index 58433c8c5b..07d406e12f 100644
--- a/locale/programs/charmap.c
+++ b/locale/programs/charmap.c
@@ -904,9 +904,9 @@  number of bytes for byte sequence of beginning and end of range not the same: %d
 	(struct width_rule *) obstack_alloc (&result->mem_pool,
 					     (new_size
 					      * sizeof (struct width_rule)));
-
-      memcpy (new_rules, result->width_rules,
-	      result->nwidth_rules_max * sizeof (struct width_rule));
+      if (result->width_rules != NULL)
+	memcpy (new_rules, result->width_rules,
+		result->nwidth_rules_max * sizeof (struct width_rule));
 
       result->width_rules = new_rules;
       result->nwidth_rules_max = new_size;