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UPSTREAM: firmware: arm_ffa: Explicitly cast return value from FFA_VERSION before comparison

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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: 3bbfe98710 ("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>
Change-Id: I383762ec971bce54f3d8aef564ebfca3b3ab2a0e
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
(cherry picked from commit cecf6a504137aa238d768ae440a1f6488cb2f436)
Signed-off-by: Andrei Homescu <ahomescu@xwf.google.com>
Bug: 435501117
This commit is contained in:
Sudeep Holla
2025-02-21 09:56:31 +00:00
committed by Andrei Homescu (xWF)
parent e5a17398e4
commit 67ff14c5d0
1 changed files with 1 additions and 1 deletions
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drivers/firmware/arm_ffa/driver.c
+1 -1
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@@ -121,7 +121,7 @@ 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;
}