[vdr] Valgrind warnings with LCARS OSD

Marko Mäkelä marko.makela at iki.fi
Sat Nov 16 18:13:27 CET 2013


Hi Klaus,

>Thanks for debugging this!
>Please try whether this fixes it:
>
>--- skinlcars.c
>+++ skinlcars.c
>@@ -900,6 +900,15 @@
>   ys03 = ys04 - Gap;
>   ys05 = yb15;
>
>+  // The item area (just to have them initialized, actual setting will be done in SetMenuCategory():
>+
>+  xi00 = 0;
>+  xi01 = 0;
>+  xi02 = 0;
>+  xi03 = 1;
>+  yi00 = 0;
>+  yi01 = 1;
>+
>   // The color buttons in submenus:
>   xb00 = xa06;
>   xb15 = xa07;

After applying this fix, the only Valgrind warnings I got from VDR were 
bogus-looking ones: the cRecording::cRecording (based on my reading of 
the disassembly, gcc's built-in version of strcmp() doing a 32-bit 
access that goes 2 bytes beyond the end of the string), and a few 
bogus-looking warnings on ioctl(). 3 of them were complaining about 
"invalid pointer" 0x0 or 0x1 for DirectFB calls, and the 4th one was 
this:

==7120== Syscall param ioctl(arg) contains uninitialised byte(s)
==7120==    at 0x436AA99: ioctl (syscall-template.S:82)
==7120==    by 0x80CB31A: cDvbDevice::SetPid(cDevice::cPidHandle*, int, 
bool) (dvbdevice.c:1394)
==7120==    by 0x80C22B4: cDevice::DelPid(int, cDevice::ePidType) 
(device.c:544)
==7120==    by 0x80C4047: cDevice::Detach(cReceiver*) (device.c:1690)
==7120==    by 0x8116605: cReceiver::Detach() (receiver.c:89)
==7120==    by 0x42B3E45: (below main) (libc-start.c:228)

	CHECK(ioctl(Handle->handle, DMX_STOP));

#define CHECK(s) { if ((s) < 0) LOG_ERROR; } // used for 'ioctl()' calls

Given that Handle->handle is a signed integer (file handle), the 
Valgrind warning should be for DMX_STOP, which does not look like a 
pointer to me. Maybe the constant happens to coincide with the address 
of some memory block (not too hard with only 32 bits of address space).  
Or perhaps Valgrind is misinterpreting the number of arguments to 
ioctl().

I switched back to using LCARS, and did not experience any crashes yet 
after applying the patch, no matter how much I played with the Menu and 
Recordings buttons. So, the patch seems to work. Thank you!

	Marko



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