Re: [PATCH] selftests/nolibc: avoid buffer underrun in space printing

On Wed, Jul 26, 2023 at 08:08:13AM +0200, Thomas Weißschuh wrote:

If the test description is longer than the status alignment the parameter 'n' to putcharn() would lead to a signed underflow that then gets converted to a very large unsigned value. This in turn leads out-of-bound writes in memset() crashing the application.

The failure case of EXPECT_PTRER() used in "mmap_bad" exhibits this exact behavior.

Fixes: 8a27526f49f9 ("selftests/nolibc: add EXPECT_PTREQ, EXPECT_PTRNE and EXPECT_PTRER") Signed-off-by: Thomas Weißschuh linux@weissschuh.net

Applied, thank you Thomas! Willy