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| author | David Laight <david.laight.linux@gmail.com> | 2026-03-02 10:17:58 +0000 |
|---|---|---|
| committer | Thomas Weißschuh <linux@weissschuh.net> | 2026-03-20 17:46:04 +0100 |
| commit | 4ea2dedd502e2b4bfa8a47f2aaaaac4eab01e00d (patch) | |
| tree | c497cdf4065c3b67134deafdd589f87cf952417d | |
| parent | f36e1ec61a6adb135d1b4021bc849c6acb96f50c (diff) | |
| download | linux-4ea2dedd502e2b4bfa8a47f2aaaaac4eab01e00d.tar.gz linux-4ea2dedd502e2b4bfa8a47f2aaaaac4eab01e00d.zip | |
selftests/nolibc: Check that snprintf() doesn't write beyond the buffer end
Fill buf[] with known data and check the vsnprintf() doesn't write
beyond the specified buffer length.
Would have picked up the bug in field padding.
Signed-off-by: David Laight <david.laight.linux@gmail.com>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://patch.msgid.link/20260302101815.3043-7-david.laight.linux@gmail.com
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
| -rw-r--r-- | tools/testing/selftests/nolibc/nolibc-test.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c index 154cc5711a4c..5dc0edfe8d9a 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -1679,6 +1679,10 @@ static int expect_vfprintf(int llen, const char *expected, const char *fmt, ...) va_list args; ssize_t w, expected_len; + /* Fill and terminate buf[] to check for overlong/absent writes */ + memset(buf, 0xa5, sizeof(buf) - 1); + buf[sizeof(buf) - 1] = 0; + va_start(args, fmt); /* Limit buffer length to test truncation */ w = vsnprintf(buf, VFPRINTF_LEN + 1, fmt, args); @@ -1710,6 +1714,15 @@ static int expect_vfprintf(int llen, const char *expected, const char *fmt, ...) return 1; } + /* Check for any overwrites after the actual data. */ + while (++cmp_len < sizeof(buf) - 1) { + if ((unsigned char)buf[cmp_len] != 0xa5) { + llen += printf(" overwrote buf[%d] with 0x%x", cmp_len, buf[cmp_len]); + result(llen, FAIL); + return 1; + } + } + result(llen, OK); return 0; } |