On Tue, 2014-08-19 at 18:50 -0400, Camm Maguire wrote: > mprotect failure: 0xd49000 305430528 : Cannot allocate memory > sgc disabled: Cannot allocate memory
I've now repro'd this (on a system running 3.10-0.bpo.2-armmp). (it the dumps me to some gcl prompt which I don't seem to be able to exit ;-)) Experimentally it seems like the benign change you referred to was the addition of __stack_chk_guard=random_ulong()? I think the enablement of stack protection is very far from benign in this context, since it plays various memory management tricks and adds guard pages etc. I don't know much about stack protector, but overriding __stack_chk_guard in main() seems odd to me, I'd expect it to be done by libc but perhaps that is because you are writing a language runtime? Are you using some magic compiler or linker options? I've tried to to write a simplified test case but my (rather too basic) attempts don't seem to be doing the trick. TBH I think you are going to need the assistance of someone who knows more about gcc/glibc/stack-protector than me, right now I don't think the kernel angle is the one most likely to produce fruit. > and when run under strace -f will show the brk calls and mprotect calls > which fail. They seem to be quite large (hundreds of MB) compared to the other such calls -- is that expected? > Oddly enough, when run under gdb, something is done to the > runtime environment which prevents the failure from occurring, a mystery > to me. FWIW I get a SEGV. (gdb) bt #0 0x0007f348 in memprotect_test () at sgbc.c:957 #1 0x00084258 in do_memprotect_test () at sgbc.c:1000 #2 memprotect_test_reset () at sgbc.c:1019 #3 0x000b271e in gcl_init_alloc (cs_start=<optimized out>) at alloc.c:1090 #4 0x00021914 in main (argc=1, argv=0xbefffd14, envp=0xbefffd1c) at main.c:357 The call to gcl_init_alloc is before "__stack_chk_guard=random_ulong()", but these functions seem to relate to memprotect. Not sure what is going on there, but perhaps the stack trace gives you a clue. Ian. -- To UNSUBSCRIBE, email to debian-arm-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/1408934407.30706.42.ca...@hellion.org.uk
