From b427514f689d71071806eb75777f5dec322e8925 Mon Sep 17 00:00:00 2001
From: Marvin Friedrich <contact@marvinf.com>
Date: Mon, 23 Dec 2024 02:13:55 +0100
Subject: [PATCH] vfs: Fix bounds check on kmesg read

---
 kernel/fs/vfs.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/fs/vfs.c b/kernel/fs/vfs.c
index b724a2e..21607b8 100644
--- a/kernel/fs/vfs.c
+++ b/kernel/fs/vfs.c
@@ -30,8 +30,11 @@ usize kmesg_cap;
 
 isize terminal_kmesg_read(Handle* self, FileDescriptor* fd, void* output_buffer, usize amount, off_t offset)
 {
-	if (amount > kmesg_len)
-		amount = kmesg_len;
+	if (offset > kmesg_len)
+		return 0;
+
+	if (offset + amount > kmesg_len)
+		amount = kmesg_len - offset;
 
 	memcpy(output_buffer, kmesg_buffer + offset, amount);
 	return amount;