6.14-stable review patch. If anyone has any objections, please let me know.
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From: Sudeep Holla sudeep.holla@arm.com
[ Upstream commit cecf6a504137aa238d768ae440a1f6488cb2f436 ]
The return value ver.a0 is unsigned long type and FFA_RET_NOT_SUPPORTED is a negative value.
Since the return value from the firmware can be just 32-bit even on 64-bit systems as FFA specification mentions it as int32 error code in w0 register, explicitly casting to s32 ensures correct sign interpretation when comparing against a signed error code FFA_RET_NOT_SUPPORTED.
Without casting, comparison between unsigned long and a negative constant could lead to unintended results due to type promotions.
Fixes: 3bbfe9871005 ("firmware: arm_ffa: Add initial Arm FFA driver support") Reported-by: Andrei Homescu ahomescu@google.com Message-Id: 20250221095633.506678-1-sudeep.holla@arm.com Signed-off-by: Sudeep Holla sudeep.holla@arm.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/firmware/arm_ffa/driver.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c index 8aa05bbab5c8d..ce1ec015e076b 100644 --- a/drivers/firmware/arm_ffa/driver.c +++ b/drivers/firmware/arm_ffa/driver.c @@ -145,7 +145,7 @@ static int ffa_version_check(u32 *version) .a0 = FFA_VERSION, .a1 = FFA_DRIVER_VERSION, }, &ver);
- if (ver.a0 == FFA_RET_NOT_SUPPORTED) { + if ((s32)ver.a0 == FFA_RET_NOT_SUPPORTED) { pr_info("FFA_VERSION returned not supported\n"); return -EOPNOTSUPP; }