[PATCH 5.13 119/127] riscv: Fix a number of free'd resources in init_resources()

[Sasha Levin]

From: Petr Pavlu <petr.pavlu@xxxxxxxx>

[ Upstream commit aa3e1ba32e553e611a58145c2eb349802feaa6eb ]

Function init_resources() allocates a boot memory block to hold an array of
resources which it adds to iomem_resource. The array is filled in from its
end and the function then attempts to free any unused memory at the
beginning. The problem is that size of the unused memory is incorrectly
calculated and this can result in releasing memory which is in use by
active resources. Their data then gets corrupted later when the memory is
reused by a different part of the system.

Fix the size of the released memory to correctly match the number of unused
resource entries.

Fixes: ffe0e5261268 ("RISC-V: Improve init_resources()")
Signed-off-by: Petr Pavlu <petr.pavlu@xxxxxxxx>
Reviewed-by: Sunil V L <sunilvl@xxxxxxxxxxxxxxxx>
Acked-by: Nick Kossifidis <mick@xxxxxxxxxxxx>
Tested-by: Sunil V L <sunilvl@xxxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 arch/riscv/kernel/setup.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 9a1b7a0603b2..f2a9cd4284b0 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -230,8 +230,8 @@ static void __init init_resources(void)
 	}
 
 	/* Clean-up any unused pre-allocated resources */
-	mem_res_sz = (num_resources - res_idx + 1) * sizeof(*mem_res);
-	memblock_free(__pa(mem_res), mem_res_sz);
+	if (res_idx >= 0)
+		memblock_free(__pa(mem_res), (res_idx + 1) * sizeof(*mem_res));
 	return;
 
  error:
-- 
2.30.2