On Thursday, January 26, 2012, David Henningsson wrote: > Hi, > > I'm trying to run PulseAudio under valgrind, and I think valgrind is > reporting a false positive; i e, it reports "Conditional jump or move > depend on uninitialised value(s)" where in fact the value seems to be > perfectly initialised and correct. > > I've tracked it down to function snd_ctl_hw_elem_tlv in alsa-lib [1]. As > you can see, if the ioctl command is SNDRV_CTL_IOCTL_TLV_READ, the > kernel writes X bytes into output, where X = 4 * sizeof(unsigned int) + > the number in output[3] (if output is an array of unsigned ints). > > I'm a little unsure of how to proceed with this?
You need to mess with PRE(sys_ioctl) and POST(sys_ioctl) in syswrap-linux.c. The PRE wrapper needs to check that the written (by the kernel) area is addressible, using PRE_MEM_WRITE. The POST wrapper needs to mark the data written after the call using POST_MEM_WRITE. See top level README_MISSING_SYSCALL_OR_IOCTL for more details. Unfortunately both PRE(sys_ioctl) and POST(sys_ioctl) are not entirely straightforward, due to the vast number and variety of ioctls available. J ------------------------------------------------------------------------------ Keep Your Developer Skills Current with LearnDevNow! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-d2d _______________________________________________ Valgrind-users mailing list Valgrind-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/valgrind-users
