[PATCH v1 1/1] pstore/ram: Fix crash when setting number of cpus to an odd number

From: Weichen Chen
Date: Thu Feb 23 2023 - 21:38:26 EST


When the number of cpu cores is adjusted to 7 or other odd numbers,
the zone size will become an odd number.
The address of the zone will become:
addr of zone0 = BASE
addr of zone1 = BASE + zone_size
addr of zone2 = BASE + zone_size*2
...
The address of zone1/3/5/7 will be mapped to non-alignment va.
Eventually crashes will occur when accessing these va.

So, use ALIGN_DOWN() to make sure the zone size is even
to avoid this bug.

Signed-off-by: Weichen Chen <weichen.chen@xxxxxxxxxxxx>
---
fs/pstore/ram.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index ade66dbe5f39..fc57ac97e506 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -528,6 +528,7 @@ static int ramoops_init_przs(const char *name,
}

zone_sz = mem_sz / *cnt;
+ zone_sz = ALIGN_DOWN(zone_sz, 2);
if (!zone_sz) {
dev_err(dev, "%s zone size == 0\n", name);
goto fail;
--
2.18.0