November 2006 - Darwin-kernel

Kernel log: app uses send/recv on a pipe
by Tomasz Kukielka 29 Nov '06

29 Nov '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Thread-index: AccTgPfzNlRD3n90EdunVQAX8i08Wg== Thread-topic: Kernel log: app uses send/recv on a pipe User-agent: Microsoft-Entourage/11.2.5.060620 Hi, I noticed the following kernel message in system log: Nov 28 20:10:42 TK-MB kernel[0]: CommandDroplet[1993] uses send/recv on a pipe CommandDroplet is the application that I develop as part of OnMyCommand which wraps Unix or AppleScript scripts with some GUI. I have been experimenting with it recently trying to make popen execution non-blocking. The problem is with pipe caching (you cannot work it around) which locks the reading and you get stuck in in fread (or fgets). I wanted to improve it but nothing seemed to work until I created a CFSocket on the file description from the stream. It works beautifully as a CFRunLoop source - providing a data in callback and not blocking. But the kernel message is a signal that there might be something wrong with it. See below for the code I used. When I #undef USE_CFSOCKET the kernel does not complain. I would really hate to go back to the previous synchronous/blocking code. Thanks, Tom http://www.abracode.com/free/cmworkshop/ bool POpenExecutor::Execute( const char *inCommand ) { if(inCommand == NULL) return true; FILE *fp = popen( inCommand, "r" ); if ( fp != NULL ) { #ifdef USE_CFSOCKET CFSocketContext context; context.version = 0; context.info = this; context.retain = NULL; context.release = NULL; context.copyDescription = NULL; int fileDesc = fileno(fp); mFileDescSocket = ::CFSocketCreateWithNative( kCFAllocatorDefault, fileDesc, kCFSocketDataCallBack, PopenCFSocketCallback, &context); if(mFileDescSocket != NULL) { mSource = ::CFSocketCreateRunLoopSource(kCFAllocatorDefault, mFileDescSocket, 0); if(mSource != NULL) ::CFRunLoopAddSource( ::CFRunLoopGetCurrent(), mSource, kCFRunLoopDefaultMode ); } return false; //not finished yet #else //USE_CFSOCKET static char oneLine[1024]; oneLine[0] = 0; do { fgets (oneLine, sizeof(oneLine), fp); } while( feof(fp) == 0 ); (void) pclose( fp ); return true; //finished #endif //USE_CFSOCKET } return true; //error condition. finished } _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

1 0

Re: Deleting BSD Flags files
by Jeffrey Ellis 27 Nov '06

27 Nov '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Thread-index: AccScRxfWxIM5H5kEduwigANk0QgEg== Thread-topic: Deleting BSD Flags files User-agent: Microsoft-Entourage/11.2.5.060620 on 11/27/06 12:02 PM, Quinn <eskimo1(a)apple.com> wrote: > At 19:20 -0800 25/11/06, William Kucharski wrote: >> To remove the file you have to boot single-user [...] > > To boot single user, restart and then hold down command-S. That will > dump you into a full screen terminal window. Follow the on-screen > instructions to mount the root volume read/write, then continue from > there. > > If the files aren't on the root volume... well, that makes things harder (-: > > S+E > -- > Quinn "The Eskimo!" Thanks very much, Quinn :) All My Best, Jeffrey _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

1 0

Re: [Solved] Re: Kernel Panic Cluedo
by Terry Lambert 27 Nov '06

27 Nov '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On Nov 27, 2006, at 3:58 AM, Andrew Gallatin wrote: It could be cool if there was a Kernel simulator with memory protection... Protection of what? Read/write memory in the kernel map is freely writable by any code within the kernel; this is what being a "monolithic" kernel is all about. Optional redzones, as well as use-after-free, use of uninitialized data, etc, would be welcome. Solaris does this with boot-time tunables (kmem_flags), and FreeBSD and linux do much of this with compile time options. A redzone may have caught Stephane's corruption as it happened.. -- Terry _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… Michael Smith writes: Stephane wrote: There is a lot of this type of checking available for allocated memory (assuming it was allocated memory) with compile time options already. See the use of "MACH_ASSERT" and "zfree_clear" at the top of osfmk/ kern/zalloc.c, and other code for memory allocation/usage verification. It doesn't deal with the alignment of allocations against page boundaries with unmapped pages adjacent to deal with underflow/ overflow trapping (necessary because hardware fails to support sub- page memory protection), but it covers most of the other bases. There's also a lot you'd get from compiling a DEBUG kernel, which mostly nobody does. For use of uninitialized data, the M_ZERO flag is your friend (anything stronger requires compiler help). Meanwhile, code donations for things like this - particularly, redzones and page end alignment - welcome! Just make sure there aren't performance penalties in the default case... PS: Also welcome is hardware that has an implicit concept of sub-page- sized type-stable memory mapping regions to allow trapping on buffer underflow/overflow over alignment boundaries (i.e. you might miss an over/underflow to the next alignment boundary, but hardware help would reall be the best bet on something like this). This email sent to site_archiver(a)lists.apple.com

1 0

Re: [Solved] Re: Kernel Panic Cluedo
by Andrew Gallatin 27 Nov '06

27 Nov '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Michael Smith writes: > Stephane wrote: > > > > It could be cool if there was a Kernel simulator with memory > > protection... > > Protection of what? Read/write memory in the kernel map is freely > writable by any code within the kernel; this is what being a > "monolithic" kernel is all about. Optional redzones, as well as use-after-free, use of uninitialized data, etc, would be welcome. Solaris does this with boot-time tunables (kmem_flags), and FreeBSD and linux do much of this with compile time options. A redzone may have caught Stephane's corruption as it happened.. Drew _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

1 0

Re: Deleting BSD Flags files
by Quinn 27 Nov '06

27 Nov '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com If the files aren't on the root volume... well, that makes things harder (-: S+E -- Quinn "The Eskimo!" <http://www.apple.com/developer/> Apple Developer Relations, Developer Technical Support, Core OS/Hardware _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… At 19:20 -0800 25/11/06, William Kucharski wrote: To remove the file you have to boot single-user [...] To boot single user, restart and then hold down command-S. That will dump you into a full screen terminal window. Follow the on-screen instructions to mount the root volume read/write, then continue from there. This email sent to site_archiver(a)lists.apple.com

1 0

Re: Deleting BSD Flags files
by Josh Graessley 26 Nov '06

26 Nov '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com -josh On Nov 25, 2006, at 7:20 PM, William Kucharski wrote: chflags noschg nosappnd nosunlnk <file>; rm -f <file> _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com Another option is to recompile the kernel with a version of the filesystem that ignores those flags. You have to boot into single-user mode to remove the sappnd or schg flags. To remove the file you have to boot single-user, remove the applied flags, then remove the files. The system won't allow you to remove the files until you unset the flags. If you don't feel like finding out which flags are set ("ls -lo"), then this should work from single user-mode: William Kucharski kucharsk(a)mac.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/jgraessley% 40apple.com This email sent to jgraessley(a)apple.com smime.p7s

1 0

Re: Deleting BSD Flags files
by William Kucharski 26 Nov '06

26 Nov '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com You have to boot into single-user mode to remove the sappnd or schg flags. To remove the file you have to boot single-user, remove the applied flags, then remove the files. The system won't allow you to remove the files until you unset the flags. If you don't feel like finding out which flags are set ("ls -lo"), then this should work from single user-mode: chflags noschg nosappnd nosunlnk <file>; rm -f <file> William Kucharski kucharsk(a)mac.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

1 0

Deleting BSD Flags files
by Jeffrey Ellis 26 Nov '06

26 Nov '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Thread-index: AccRB/g0NrGEuHz7EdufNQANk0QgEg== Thread-topic: Deleting BSD Flags files User-agent: Microsoft-Entourage/11.2.5.060620 Hi-- I'm having a bit of a problem deleting some files I was working with to test various BSD flags. I was told they could be deleted by booting into single-user mode, but so far, that hasn't worked. The closest I've come is to "sudo rm" one of the files. It asks me something like "override sappend, arch for [filename]? I respond "y" or "yes" and it says "operation not permitted". Is there a good way to delete these files? I don't actually have another drive to boot from at the moment... All My Best, Jeffrey _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

1 0

Re: [Solved] Re: Kernel Panic Cluedo
by Michael Smith 24 Nov '06

24 Nov '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com User-agent: Thunderbird 1.5.0.8 (Macintosh/20061025) In the meantime, two-machine debugging is where it's at. 8) = Mike _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… Stephane Sudre wrote: I just don't care about this. I'm just dreaming of a solution which would make it easier to track Kernel Panics. The positive output of this bug is that from what I've seen it's apparently way easier to reproduce a memory issue on an Intel Mac than on a PowerPC Mac. I haven't seen any evidence of, and can't think offhand of a mechanism whereby this could be true. It's an interesting theory. This email sent to site_archiver(a)lists.apple.com

1 0

Re: [Solved] Re: Kernel Panic Cluedo
by Stephane Sudre 23 Nov '06

23 Nov '06

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On jeudi, novembre 23, 2006, at 08:14 PM, Michael Smith wrote: On Nov 22, 2006, at 6:04 PM, Michael Smith wrote: Stephane wrote: It turned out to be a copyin of a bigger size than required. I can see plenty of usage for this "science fiction" simulator thing. _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… Stephane wrote: When you do some bad things in your Kernel Extension (such as writing where you should not, reading a bit too far in buffers, etc...), should a Kernel Panic occur in your Kernel Extension or can it occur later? It depends on what you damage. If you read/write completely out of bounds, your code will fail. But if you destroy a pointer belonging to someone else, there is no way for the hardware/kernel to know a) that that's what you're doing, or b) to blame you when some other code attempts to use it. It could be cool if there was a Kernel simulator with memory protection... Protection of what? Read/write memory in the kernel map is freely writable by any code within the kernel; this is what being a "monolithic" kernel is all about. Well, since this would be a simulator, ideally you would be able to compile a specific version of a kext to run on it and you could tag specific data as protected. Given how much vilifiction Darwin has received for being a "microkernel" because we "all know" how inefficient they are, I see this rapidly becoming amusing. I just don't care about this. I'm just dreaming of a solution which would make it easier to track Kernel Panics. The positive output of this bug is that from what I've seen it's apparently way easier to reproduce a memory issue on an Intel Mac than on a PowerPC Mac. This email sent to site_archiver(a)lists.apple.com

1 0