[PATCH 0/1] lib/vsprintf:

From: Masami Hiramatsu (Google)

Date: Thu Mar 19 2026 - 23:51:56 EST


Hi,

Here is a pair of patches to fix vsnprintf().

- Fix to limit the size of width and precision.
- Warn if the return size is over INT_MAX.

Recently we discussed snprintf() usage in bootconfig and found snprintf()
design has a problem[1]. It returns the required or printed size in 'int'
but the maxlen is passed by 'size_t'. The maxlen is already limited by
INT_MAX, but if the expected print size becomes bigger than INT_MAX,
it can return negative value. We also found width and precision size check
does not work.

[1] https://lore.kernel.org/all/20260317121507.30735331@xxxxxxxxxxxxxxxxxx/

Thank you,

---

Masami Hiramatsu (Google) (2):
lib/vsprintf: Fix to check field_width and precision
lib/vsprintf: Limit the returning size to INT_MAX


lib/vsprintf.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

--
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>