[PATCH] hostap: avoid uninitialized variable use in hfa384x_get_rid
The driver reads a value from hfa384x_from_bap(), which may fail,
and then assigns the value to a local variable. gcc detects that
in in the failure case, the 'rlen' variable now contains
uninitialized data:
In file included from
../drivers/net/wireless/intersil/hostap/hostap_pci.c:220:0:
drivers/net/wireless/intersil/hostap/hostap_hw.c: In function 'hfa384x_get_rid':
drivers/net/wireless/intersil/hostap/hostap_hw.c:842:5: warning: 'rec' may be
used uninitialized in this function [-Wmaybe-uninitialized]
if (le16_to_cpu(rec.len) == 0) {
To ensure we get consistent error handling here, this changes the code
to only set rlen if we actually read data correctly, which also takes
care of the warning.
Signed-off-by: Arnd Bergmann
---
drivers/net/wireless/intersil/hostap/hostap_hw.c | 11 +++
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/net/wireless/intersil/hostap/hostap_hw.c
b/drivers/net/wireless/intersil/hostap/hostap_hw.c
index 6df3ee561d52..6dbf8ee9490a 100644
--- a/drivers/net/wireless/intersil/hostap/hostap_hw.c
+++ b/drivers/net/wireless/intersil/hostap/hostap_hw.c
@@ -839,12 +839,15 @@ static int hfa384x_get_rid(struct net_device *dev, u16
rid, void *buf, int len,
if (!res)
res = hfa384x_from_bap(dev, BAP0, &rec, sizeof(rec));
- if (le16_to_cpu(rec.len) == 0) {
- /* RID not available */
- res = -ENODATA;
+ if (!res) {
+ if (le16_to_cpu(rec.len) == 0) {
+ /* RID not available */
+ res = -ENODATA;
+ }
+
+ rlen = (le16_to_cpu(rec.len) - 1) * 2;
}
- rlen = (le16_to_cpu(rec.len) - 1) * 2;
if (!res && exact_len && rlen != len) {
printk(KERN_DEBUG "%s: hfa384x_get_rid - RID len mismatch: "
"rid=0x%04x, len=%d (expected %d)\n",
--
2.7.0
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Re: [PATCH] hostap: avoid uninitialized variable use in hfa384x_get_rid
On Wed, Jan 27, 2016 at 02:45:26PM +0100, Arnd Bergmann wrote:
> To ensure we get consistent error handling here, this changes the code
> to only set rlen if we actually read data correctly, which also takes
> care of the warning.
It may be a good idea to do the job better. Looking at the code:
struct hfa384x_rid_hdr rec;
spin_lock_bh(&local->baplock);
res = hfa384x_setup_bap(dev, BAP0, rid, 0);
if (!res)
res = hfa384x_from_bap(dev, BAP0, &rec, sizeof(rec));
The only thing which initialises any of "rec" is that function call.
The following lines are:
if (le16_to_cpu(rec.len) == 0) {
/* RID not available */
res = -ENODATA;
}
rlen = (le16_to_cpu(rec.len) - 1) * 2;
So, why give the compiler a hard time as you're doing, why make the code
harder to read. What's wrong with:
spin_lock_bh(&local->baplock);
res = hfa384x_setup_bap(dev, BAP0, rid, 0);
if (res)
goto unlock;
res = hfa384x_from_bap(dev, BAP0, &rec, sizeof(rec));
if (res)
goto unlock;
if (le16_to_cpu(rec.len) == 0) {
/* RID not available */
res = -ENODATA;
goto unlock;
}
rlen = (le16_to_cpu(rec.len) - 1) * 2;
if (exact_len && rlen != len) {
printk(KERN_DEBUG "%s: hfa384x_get_rid - RID len mismatch:
rid=0x%04x, len=%d (expected %d)\n",
dev->name, rid, rlen, len);
res = -ENODATA;
goto unlock;
}
res = hfa384x_from_bap(dev, BAP0, buf, len);
unlock:
spin_unlock_bh(&local->baplock);
?
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Re: [PATCH] hostap: avoid uninitialized variable use in hfa384x_get_rid
On Wednesday 27 January 2016 19:26:13 Russell King - ARM Linux wrote:
> On Wed, Jan 27, 2016 at 02:45:26PM +0100, Arnd Bergmann wrote:
> So, why give the compiler a hard time as you're doing, why make the code
> harder to read. What's wrong with:
>
> spin_lock_bh(&local->baplock);
>
> res = hfa384x_setup_bap(dev, BAP0, rid, 0);
> if (res)
> goto unlock;
>
> res = hfa384x_from_bap(dev, BAP0, &rec, sizeof(rec));
> if (res)
> goto unlock;
>
> if (le16_to_cpu(rec.len) == 0) {
> /* RID not available */
> res = -ENODATA;
> goto unlock;
> }
>
> rlen = (le16_to_cpu(rec.len) - 1) * 2;
> if (exact_len && rlen != len) {
> printk(KERN_DEBUG "%s: hfa384x_get_rid - RID len mismatch:
> rid=0x%04x, len=%d (expected %d)\n",
>dev->name, rid, rlen, len);
> res = -ENODATA;
> goto unlock;
> }
>
> res = hfa384x_from_bap(dev, BAP0, buf, len);
> unlock:
> spin_unlock_bh(&local->baplock);
>
> ?
>
Good idea, I'll send a new version.
Arnd
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