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MIPS: Loongson64: env: Check UARTs passed by LEFI cautiously

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Some firmware does not set nr_uarts properly and passes empty items.
Iterate at most min(system->nr_uarts, MAX_UARTS) items to prevent
out-of-bounds access, and ignore UARTs with addr 0 silently.

Meanwhile, our DT only works with UPIO_MEM but theoretically firmware
may pass other IO types, so explicitly check against that.

Tested on Loongson-LS3A4000-7A1000-NUC-SE.

Fixes: 3989ed4184 ("MIPS: Loongson64: env: Fixup serial clock-frequency when using LEFI")
Cc: stable@vger.kernel.org
Reviewed-by: Yao Zi <me@ziyao.cc>
Signed-off-by: Rong Zhang <rongrong@oss.cipunited.com>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
This commit is contained in:
Rong Zhang 2026-03-16 01:28:22 +08:00 committed by Thomas Bogendoerfer
parent 6de23f81a5
commit 35d8945bf9
1 changed files with 17 additions and 1 deletions
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18
arch/mips/loongson64/env.c
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@ -17,7 +17,9 @@
#include <linux/dma-map-ops.h>
#include <linux/export.h>
#include <linux/libfdt.h>
#include <linux/minmax.h>
#include <linux/pci_ids.h>
#include <linux/serial_core.h>
#include <linux/string_choices.h>
#include <asm/bootinfo.h>
#include <loongson.h>
@ -106,9 +108,23 @@ static void __init lefi_fixup_fdt(struct system_loongson *system)
is_loongson64g = (read_c0_prid() & PRID_IMP_MASK) == PRID_IMP_LOONGSON_64G;
for (i = 0; i < system->nr_uarts; i++) {
for (i = 0; i < min(system->nr_uarts, MAX_UARTS); i++) {
uartdev = &system->uarts[i];
/*
* Some firmware does not set nr_uarts properly and passes empty
* items. Ignore them silently.
*/
if (uartdev->uart_base == 0)
continue;
/* Our DT only works with UPIO_MEM. */
if (uartdev->iotype != UPIO_MEM) {
pr_warn("Ignore UART 0x%llx with iotype %u passed by firmware\n",
uartdev->uart_base, uartdev->iotype);
continue;
}
ret = lefi_fixup_fdt_serial(fdt_buf, uartdev->uart_base,
uartdev->uartclk);
/*