From: Thorsten Blum <thorsten.blum@linux.dev>
To: Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Pekka Enberg <penberg@cs.helsinki.fi>,
Yinghai Lu <yinghai@kernel.org>
Cc: Thorsten Blum <thorsten.blum@linux.dev>,
stable@vger.kernel.org, "H. Peter Anvin" <hpa@linux.intel.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH] x86/boot: validate console=uart8250 baud rate to avoid early boot hang
Date: Thu, 14 May 2026 16:30:15 +0200 [thread overview]
Message-ID: <20260514143014.516303-3-thorsten.blum@linux.dev> (raw)
When the baud rate is empty, 0, invalid, or overflows to 0 when stored
as an int, the system will hang during early boot because of a division
by zero in early_serial_init().
Fall back to DEFAULT_BAUD when the resulting baud rate is 0 to prevent
an early system hang.
Fixes: ce0aa5dd20e4 ("x86, setup: Make the setup code also accept console=uart8250")
Cc: stable@vger.kernel.org
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
arch/x86/boot/early_serial_console.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/arch/x86/boot/early_serial_console.c b/arch/x86/boot/early_serial_console.c
index 023bf1c3de8b..28a887af430d 100644
--- a/arch/x86/boot/early_serial_console.c
+++ b/arch/x86/boot/early_serial_console.c
@@ -117,7 +117,7 @@ static unsigned int probe_baud(int port)
static void parse_console_uart8250(void)
{
char optstr[64], *options;
- int baud = DEFAULT_BAUD;
+ int baud;
int port = 0;
/*
@@ -136,9 +136,11 @@ static void parse_console_uart8250(void)
else
return;
- if (options && (options[0] == ','))
- baud = simple_strtoull(options + 1, &options, 0);
- else
+ if (options && (options[0] == ',')) {
+ baud = simple_strtoull(options + 1, NULL, 0);
+ if (!baud)
+ baud = DEFAULT_BAUD;
+ } else
baud = probe_baud(port);
if (port)
reply other threads:[~2026-05-14 14:31 UTC|newest]
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