From: Sudeep Holla Date: Fri, 21 Feb 2025 09:56:31 +0000 (+0000) Subject: firmware: arm_ffa: Explicitly cast return value from FFA_VERSION before comparison X-Git-Tag: v6.15-rc1~158^2~14^2~3 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cecf6a504137aa238d768ae440a1f6488cb2f436;p=thirdparty%2Flinux.git firmware: arm_ffa: Explicitly cast return value from FFA_VERSION before comparison 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 Message-Id: <20250221095633.506678-1-sudeep.holla@arm.com> Signed-off-by: Sudeep Holla --- diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c index f3ca703a44413..7c288ae74f97c 100644 --- a/drivers/firmware/arm_ffa/driver.c +++ b/drivers/firmware/arm_ffa/driver.c @@ -144,7 +144,7 @@ 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; }