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SubjectRe: [PATCH] PCI: mvebu: Fix uninitialized variable in mvebu_get_tgt_attr()
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On Friday 05 September 2014 11:41:22 Bjorn Helgaas wrote:
> On Fri, Aug 08, 2014 at 05:34:05PM +0200, Geert Uytterhoeven wrote:
> > drivers/pci/host/pci-mvebu.c: In function 'mvebu_get_tgt_attr':
> > drivers/pci/host/pci-mvebu.c:887:39: warning: 'rtype' may be used uninitialized in this function [-Wmaybe-uninitialized]
> > if (slot == PCI_SLOT(devfn) && type == rtype) {
> > ^
> >
> > If there's ever gonna be a configuration space or 64-bit memory space
> > entry in DT, rtype will be uninitialized, and the wrong entry may be
> > returned.
> >
> > Initialize rtype to 0 (which is an unused IORESOURCE_* type) to fix this.
> >
> > Introduced in commit 11be65472a427dcf7a11ab6e3e3628f1c6768b5b ("PCI:
> > mvebu: Adapt to the new device tree layout").
> >
> > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > ---
> > Alternatively, should the "else if (DT_FLAGS_TO_TYPE(flags) ==
> > DT_TYPE_MEM32)" just be changed to "else", assuming there can never be
> > other entries than for I/O or 32-bit memory space?
> > ---
> > drivers/pci/host/pci-mvebu.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/pci/host/pci-mvebu.c b/drivers/pci/host/pci-mvebu.c
> > index ce23e0f076b6..9515f0d13fd4 100644
> > --- a/drivers/pci/host/pci-mvebu.c
> > +++ b/drivers/pci/host/pci-mvebu.c
> > @@ -877,7 +877,7 @@ static int mvebu_get_tgt_attr(struct device_node *np, int devfn,
> > u32 flags = of_read_number(range, 1);
> > u32 slot = of_read_number(range + 1, 1);
> > u64 cpuaddr = of_read_number(range + na, pna);
> > - unsigned long rtype;
> > + unsigned long rtype = 0;
> >
> > if (DT_FLAGS_TO_TYPE(flags) == DT_TYPE_IO)
> > rtype = IORESOURCE_IO;
>
> This fix looks right to me. I added a stable tag as follows. Thomas
> and/or Jason, and you ack this?


I had a local fix for this, which I haven't gotten around to
send a proper changelog for, but it seems like a more appropriate
fix, avoiding the spurious initialization.

The other fix looks technically correct as well though.

Arnd

diff --git a/drivers/pci/host/pci-mvebu.c b/drivers/pci/host/pci-mvebu.c
index a8c6f1a92e0f..678849836649 100644
--- a/drivers/pci/host/pci-mvebu.c
+++ b/drivers/pci/host/pci-mvebu.c
@@ -883,6 +883,8 @@ static int mvebu_get_tgt_attr(struct device_node *np, int devfn,
rtype = IORESOURCE_IO;
else if (DT_FLAGS_TO_TYPE(flags) == DT_TYPE_MEM32)
rtype = IORESOURCE_MEM;
+ else
+ rtype = -1;

if (slot == PCI_SLOT(devfn) && type == rtype) {
*tgt = DT_CPUADDR_TO_TARGET(cpuaddr);


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