linux-kernel - [PATCH AUTOSEL 4.9 05/99] powerpc: Fix signedness bug in update_flash

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Date:   Sat, 16 Nov 2019 10:49:28 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Dan Carpenter <dan.carpenter@...cle.com>,
        Geoff Levand <geoff@...radead.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Sasha Levin <sashal@...nel.org>, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH AUTOSEL 4.9 05/99] powerpc: Fix signedness bug in update_flash_db()

From: Dan Carpenter <dan.carpenter@...cle.com>

[ Upstream commit 014704e6f54189a203cc14c7c0bb411b940241bc ]

The "count < sizeof(struct os_area_db)" comparison is type promoted to
size_t so negative values of "count" are treated as very high values
and we accidentally return success instead of a negative error code.

This doesn't really change runtime much but it fixes a static checker
warning.

Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Acked-by: Geoff Levand <geoff@...radead.org>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/powerpc/platforms/ps3/os-area.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/ps3/os-area.c b/arch/powerpc/platforms/ps3/os-area.c
index 3db53e8aff927..9b2ef76578f06 100644
--- a/arch/powerpc/platforms/ps3/os-area.c
+++ b/arch/powerpc/platforms/ps3/os-area.c
@@ -664,7 +664,7 @@ static int update_flash_db(void)
 	db_set_64(db, &os_area_db_id_rtc_diff, saved_params.rtc_diff);
 
 	count = os_area_flash_write(db, sizeof(struct os_area_db), pos);
-	if (count < sizeof(struct os_area_db)) {
+	if (count < 0 || count < sizeof(struct os_area_db)) {
 		pr_debug("%s: os_area_flash_write failed %zd\n", __func__,
 			 count);
 		error = count < 0 ? count : -EIO;
-- 
2.20.1