Compiler cannot infer upper bound for labels.cnt and warns about
potential buffer overflow in snprintf. Add an explicit bounds
check (... && i < MAX_LOCAL_LABELS) in the loop condition to fix the
warning.
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
.../testing/selftests/bpf/jit_disasm_helpers.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/tools/testing/selftests/bpf/jit_disasm_helpers.c b/tools/testing/selftests/bpf/jit_disasm_helpers.c
index febd6b12e372..364c557c5115 100644
--- a/tools/testing/selftests/bpf/jit_disasm_helpers.c
+++ b/tools/testing/selftests/bpf/jit_disasm_helpers.c
@@ -122,15 +122,15 @@ static int disasm_one_func(FILE *text_out, uint8_t *image, __u32 len)
pc += cnt;
}
qsort(labels.pcs, labels.cnt, sizeof(*labels.pcs), cmp_u32);
- for (i = 0; i < labels.cnt; ++i)
- /* gcc is unable to infer upper bound for labels.cnt and assumes
- * it to be U32_MAX. U32_MAX takes 10 decimal digits.
- * snprintf below prints into labels.names[*],
- * which has space only for two digits and a letter.
- * To avoid truncation warning use (i % MAX_LOCAL_LABELS),
- * which informs gcc about printed value upper bound.
- */
- snprintf(labels.names[i], sizeof(labels.names[i]), "L%d", i % MAX_LOCAL_LABELS);
+ /* gcc is unable to infer upper bound for labels.cnt and
+ * assumes it to be U32_MAX. U32_MAX takes 10 decimal digits.
+ * snprintf below prints into labels.names[*], which has space
+ * only for two digits and a letter. To avoid truncation
+ * warning use (i < MAX_LOCAL_LABELS), which informs gcc about
+ * printed value upper bound.
+ */
+ for (i = 0; i < labels.cnt && i < MAX_LOCAL_LABELS; ++i)
+ snprintf(labels.names[i], sizeof(labels.names[i]), "L%d", i);
/* now print with labels */
labels.print_phase = true;
--
2.53.0