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x86/boot: Validate console=uart8250 baud rate to fix early boot hang

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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: ce0aa5dd20 ("x86, setup: Make the setup code also accept console=uart8250")
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260713194924.126472-3-thorsten.blum@linux.dev
This commit is contained in:
Thorsten Blum 2026-07-13 21:49:25 +02:00 committed by Ingo Molnar
parent d130041a7b
commit ffa0aa5b62
1 changed files with 7 additions and 4 deletions
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11
arch/x86/boot/early_serial_console.c
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@ -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;
/*
@ -136,10 +136,13 @@ 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)
early_serial_init(port, baud);