[PATCH v2 2/5] firmware: arm_scpi: reject DVFS OPP count above MAX_DVFS_OPPS

[Xixin Liu]

scpi_dvfs_get_info() already rejected a zero opp_count, but still trusted
any larger value from the SCP firmware. The shared-memory reply only holds
MAX_DVFS_OPPS entries in buf.opps[]; a bigger count over-reads that array
and then sizes the allocated OPP table incorrectly (garbage OPPs / OOB).
The missing upper bound dates back to the original SCPI DVFS support.

Reject zero and out-of-range counts in one check and return -EINVAL.

Fixes: 8cb7cf56c9fe ("firmware: add support for ARM System Control and Power Interface(SCPI) protocol")
Signed-off-by: Xixin Liu <liuxixin at kylinos.cn>
---
 drivers/firmware/arm_scpi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/arm_scpi.c b/drivers/firmware/arm_scpi.c
index 43d6d9bbc7a9..68a730d22037 100644
--- a/drivers/firmware/arm_scpi.c
+++ b/drivers/firmware/arm_scpi.c
@@ -631,8 +631,8 @@ static struct scpi_dvfs_info *scpi_dvfs_get_info(u8 domain)
 	if (ret)
 		return ERR_PTR(ret);
 
-	if (!buf.opp_count)
-		return ERR_PTR(-ENOENT);
+	if (!buf.opp_count || buf.opp_count > MAX_DVFS_OPPS)
+		return ERR_PTR(-EINVAL);
 
 	info = kmalloc_obj(*info);
 	if (!info)
-- 
2.53.0