linux-kernel - [PATCH] PCI: Always initialize dev in pciconfig

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Message-Id: <20210803200836.500658-1-nathan@kernel.org>
Date:   Tue,  3 Aug 2021 13:08:36 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Krzysztof Wilczyński <kw@...ux.com>
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com,
        Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH] PCI: Always initialize dev in pciconfig_read

Clang warns:

drivers/pci/syscall.c:25:6: warning: variable 'dev' is used
uninitialized whenever 'if' condition is true
[-Wsometimes-uninitialized]
        if (!capable(CAP_SYS_ADMIN))
            ^~~~~~~~~~~~~~~~~~~~~~~
drivers/pci/syscall.c:81:14: note: uninitialized use occurs here
        pci_dev_put(dev);
                    ^~~
drivers/pci/syscall.c:25:2: note: remove the 'if' if its condition is
always false
        if (!capable(CAP_SYS_ADMIN))
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/pci/syscall.c:18:21: note: initialize the variable 'dev' to
silence this warning
        struct pci_dev *dev;
                           ^
                            = NULL
1 warning generated.

pci_dev_put accounts for a NULL pointer so initialize dev to NULL before
the capability check so that there is no use of uninitialized memory.

Fixes: 61a6199787d9 ("PCI: Return ~0 data on pciconfig_read() CAP_SYS_ADMIN failure")
Signed-off-by: Nathan Chancellor <nathan@...nel.org>
---
 drivers/pci/syscall.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/pci/syscall.c b/drivers/pci/syscall.c
index 525f16caed1d..61a6fe3cde21 100644
--- a/drivers/pci/syscall.c
+++ b/drivers/pci/syscall.c
@@ -22,6 +22,7 @@ SYSCALL_DEFINE5(pciconfig_read, unsigned long, bus, unsigned long, dfn,
 	int err, cfg_ret;
 
 	err = -EPERM;
+	dev = NULL;
 	if (!capable(CAP_SYS_ADMIN))
 		goto error;
 

base-commit: 21d8e94253eb09f7c94c4db00dc714efc75b8701
-- 
2.33.0.rc0