linux-kernel - [PATCH AUTOSEL 5.10 10/16] arm64: cacheinfo: Fix incorrect assignment of signed error value to unsigned fw

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Date:   Tue, 30 Aug 2022 13:23:11 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Bruno Goncalves <bgoncalv@...hat.com>,
        Will Deacon <will@...nel.org>, Sasha Levin <sashal@...nel.org>,
        catalin.marinas@....com, tglx@...utronix.de, peterz@...radead.org,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH AUTOSEL 5.10 10/16] arm64: cacheinfo: Fix incorrect assignment of signed error value to unsigned fw_level

From: Sudeep Holla <sudeep.holla@....com>

[ Upstream commit e75d18cecbb3805895d8ed64da4f78575ec96043 ]

Though acpi_find_last_cache_level() always returned signed value and the
document states it will return any errors caused by lack of a PPTT table,
it never returned negative values before.

Commit 0c80f9e165f8 ("ACPI: PPTT: Leave the table mapped for the runtime usage")
however changed it by returning -ENOENT if no PPTT was found. The value
returned from acpi_find_last_cache_level() is then assigned to unsigned
fw_level.

It will result in the number of cache leaves calculated incorrectly as
a huge value which will then cause the following warning from __alloc_pages
as the order would be great than MAX_ORDER because of incorrect and huge
cache leaves value.

  |  WARNING: CPU: 0 PID: 1 at mm/page_alloc.c:5407 __alloc_pages+0x74/0x314
  |  Modules linked in:
  |  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.19.0-10393-g7c2a8d3ac4c0 #73
  |  pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
  |  pc : __alloc_pages+0x74/0x314
  |  lr : alloc_pages+0xe8/0x318
  |  Call trace:
  |   __alloc_pages+0x74/0x314
  |   alloc_pages+0xe8/0x318
  |   kmalloc_order_trace+0x68/0x1dc
  |   __kmalloc+0x240/0x338
  |   detect_cache_attributes+0xe0/0x56c
  |   update_siblings_masks+0x38/0x284
  |   store_cpu_topology+0x78/0x84
  |   smp_prepare_cpus+0x48/0x134
  |   kernel_init_freeable+0xc4/0x14c
  |   kernel_init+0x2c/0x1b4
  |   ret_from_fork+0x10/0x20

Fix the same by changing fw_level to be signed integer and return the
error from init_cache_level() early in case of error.

Reported-and-Tested-by: Bruno Goncalves <bgoncalv@...hat.com>
Signed-off-by: Sudeep Holla <sudeep.holla@....com>
Link: https://lore.kernel.org/r/20220808084640.3165368-1-sudeep.holla@arm.com
Signed-off-by: Will Deacon <will@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm64/kernel/cacheinfo.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c
index 587543c6c51cb..97c42be71338a 100644
--- a/arch/arm64/kernel/cacheinfo.c
+++ b/arch/arm64/kernel/cacheinfo.c
@@ -45,7 +45,8 @@ static void ci_leaf_init(struct cacheinfo *this_leaf,
 
 int init_cache_level(unsigned int cpu)
 {
-	unsigned int ctype, level, leaves, fw_level;
+	unsigned int ctype, level, leaves;
+	int fw_level;
 	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
 
 	for (level = 1, leaves = 0; level <= MAX_CACHE_LEVEL; level++) {
@@ -63,6 +64,9 @@ int init_cache_level(unsigned int cpu)
 	else
 		fw_level = acpi_find_last_cache_level(cpu);
 
+	if (fw_level < 0)
+		return fw_level;
+
 	if (level < fw_level) {
 		/*
 		 * some external caches not specified in CLIDR_EL1
-- 
2.35.1