Hello Thomas Weißschuh,
The patch 5ea2bcdfbf46: "printk: ringbuffer: Add KUnit test" from Jun
12, 2025, leads to the following static checker warning:
kernel/printk/printk_ringbuffer_kunit_test.c:91 prbtest_check_data()
(unpublished script worries this an off by one)
kernel/printk/printk_ringbuffer_kunit_test.c
83 static bool prbtest_check_data(const struct prbtest_rbdata *dat)
84 {
85 unsigned int len;
86
87 /* Sane length? */
88 if (dat->len < 1 || dat->len > MAX_RBDATA_TEXT_SIZE)
89 return false;
90
--> 91 if (dat->text[dat->len] != '\0')
92 return false;
93
My question is that the prbtest_rbdata structure is declared like this:
53 /* test data structure */
54 struct prbtest_rbdata {
55 unsigned int len;
56 char text[] __counted_by(len);
57 };
The size of text is not really counted by len, it's "MAX_RBDATA_TEXT_SIZE
+ 1". The condition "if (dat->text[dat->len] != '\0')" is reading one
element beyond the __counted_by() value so something should complain if
we enable all the debugging, right?
regards,
dan carpenter
