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| author |   deraadt <deraadt@openbsd.org> | 2018-04-12 17:13:34 +0000 |
|---|---|---|
| committer | deraadt <deraadt@openbsd.org> | 2018-04-12 17:13:34 +0000 |
| commit | 003f5e42bbc90263e30dbce6eb150fc5e31b56eb (patch) | |
| tree | 04d47971c19a950593b40d0a8bba6cc3c78f0cbd /lib/libpthread/man/pthread_attr_setstackaddr.3 | |
| parent | Restore the original BSDI $Id$ strings. Those were mangled by CVS (diff) | |
| download | wireguard-openbsd-003f5e42bbc90263e30dbce6eb150fc5e31b56eb.tar.xz wireguard-openbsd-003f5e42bbc90263e30dbce6eb150fc5e31b56eb.zip | |
Implement MAP_STACK option for mmap(). Synchronous faults (pagefault and
syscall) confirm the stack register points at MAP_STACK memory, otherwise
SIGSEGV is delivered. sigaltstack() and pthread_attr_setstack() are modified
to create a MAP_STACK sub-region which satisfies alignment requirements.
Observe that MAP_STACK can only be set/cleared by mmap(), which zeroes the
contents of the region -- there is no mprotect() equivalent operation, so
there is no MAP_STACK-adding gadget.
This opportunistic software-emulation of a stack protection bit makes
stack-pivot operations during ROPchain fragile (kind of like removing a
tool from the toolbox).
original discussion with tedu, uvm work by stefan, testing by mortimer
ok kettenis
Diffstat (limited to 'lib/libpthread/man/pthread_attr_setstackaddr.3')
| -rw-r--r-- | lib/libpthread/man/pthread_attr_setstackaddr.3 | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/lib/libpthread/man/pthread_attr_setstackaddr.3 b/lib/libpthread/man/pthread_attr_setstackaddr.3 index 18b8db4b580..0c464bbf429 100644 --- a/lib/libpthread/man/pthread_attr_setstackaddr.3 +++ b/lib/libpthread/man/pthread_attr_setstackaddr.3 @@ -1,9 +1,9 @@ -.\" $OpenBSD: pthread_attr_setstackaddr.3,v 1.11 2013/06/05 03:44:50 tedu Exp $ +.\" $OpenBSD: pthread_attr_setstackaddr.3,v 1.12 2018/04/12 17:13:34 deraadt Exp $ .\" Manual page derived from TOG's UNIX98 documentation. .\" .\" David Leonard, 2000. Public Domain. .\" -.Dd $Mdocdate: June 5 2013 $ +.Dd $Mdocdate: April 12 2018 $ .Dt PTHREAD_ATTR_SETSTACKADDR 3 .Os .Sh NAME @@ -34,6 +34,17 @@ attribute specifies the location of storage to be used for the created thread's stack. The size of the storage is at least .Dv PTHREAD_STACK_MIN . +.Pp +On +.Ox +the stack must have been allocated using +.Xr mmap +with the +.Va MAP_STACK +attribute. +Otherwise, use of the stack will cause SIGABRT faults. +.Xr pthread_attr_setstack 3 +can avoid this problem because it knows the size of the stack to remap. .Sh RETURN VALUES Upon successful completion, .Fn pthread_attr_setstackaddr |