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| author | Vasily Gorbik <gor@linux.ibm.com> | 2026-04-17 15:33:43 +0300 |
|---|---|---|
| committer | Alexander Gordeev <agordeev@linux.ibm.com> | 2026-04-28 15:45:02 +0300 |
| commit | e14622a7584f9608927c59a7d6ae4a0999dc545e (patch) | |
| tree | 88e1b377ef7b563aaff15d539458d9de376b6363 | |
| parent | c366a7b5ed7564e41345c380285bd3f6cb98971b (diff) | |
| download | linux-e14622a7584f9608927c59a7d6ae4a0999dc545e.tar.xz | |
s390/debug: Reject zero-length input in debug_input_flush_fn()
debug_input_flush_fn() always copies one byte from the userspace buffer
with copy_from_user() regardless of the supplied write length. A
zero-length write therefore reads one byte beyond the caller's buffer.
If the stale byte happens to be '-' or a digit the debug log is
silently flushed. With an unmapped buffer the call returns -EFAULT.
Reject zero-length writes before copying from userspace.
Cc: stable@vger.kernel.org # v5.10+
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
| -rw-r--r-- | arch/s390/kernel/debug.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/s390/kernel/debug.c b/arch/s390/kernel/debug.c index 2612f634e826..7650f2adb5cf 100644 --- a/arch/s390/kernel/debug.c +++ b/arch/s390/kernel/debug.c @@ -1587,6 +1587,11 @@ static int debug_input_flush_fn(debug_info_t *id, struct debug_view *view, char input_buf[1]; int rc = user_len; + if (!user_len) { + rc = -EINVAL; + goto out; + } + if (user_len > 0x10000) user_len = 0x10000; if (*offset != 0) { |