CVS commit: [netbsd-10] src/sys

["Martin Husemann" <martin%netbsd.org@localhost>]

Module Name:    src
Committed By:   martin
Date:           Sat Oct 24 10:39:52 UTC 2026

Modified Files:
        src/sys/compat/netbsd32 [netbsd-10]: netbsd32_signal.c
        src/sys/kern [netbsd-10]: exec_script.c exec_subr.c kern_exec.c
            kern_fork.c

Log Message:
Pull up following revision(s) (requested by riastradh in ticket #541):

        sys/compat/netbsd32/netbsd32_signal.c: revision 1.57
        sys/kern/kern_fork.c: revision 1.235
        sys/kern/exec_subr.c: revision 1.93 (via patch)
        sys/kern/kern_exec.c: revision 1.534 (via patch)
        sys/kern/kern_exec.c: revision 1.535 (via patch)
        sys/kern/exec_script.c: revision 1.86 (via patch)

exec: Free struct exec_package::ep_emul_arg in more error paths.

We should really formalize the destruction path for these temporary
exec data structures; these error branches are all tangled messes of
spaghetti.

PR kern/60657: panic: kernel diagnostic assertion "epp->ep_emul_arg
== NULL" failed: file
"/home/riastradh/netbsd/current/src/sys/kern/kern_exec.c", line 535

Test case forthcoming (it would panic the testbed) as part of

PR kern/60653: posix_spawn(3) causes incorrect stack base information
which is how I stumbled upon this.

Test various methods of getting the process's stack base and size.
And test the effect of fork, vfork, failed execve, and posix_spawn on
them.

PR kern/60653: posix_spawn(3) causes incorrect stack base information

t_signal_and_sp: Link against libpthread unconditionally now.

Required by new test cases added for:
PR kern/60653: posix_spawn(3) causes incorrect stack base information

execve(2): Set p_stackbase in execve_runproc, not execve_loadvm.
execve_loadvm must not have side effects on the running process for
two reasons:

1. If execve(2) fails, it has to be able to back out and return to
   the calling process.  For example, the shell will execute the
   first of a series of candidate paths that works when it searches
   $PATH, and if one fails, it has to be able to move on to try the
   next.
2. The caller may be the _parent_ process -- this is the case when
   we're in posix_spawn.

Instead, it must be set in execve_runproc, after we're committed to
the exec and can't back out -- and we're definitely operating on the
process that is executing a new image, not on its parent!
p_stackbase and its assignment in exec_setup_stack, a subroutine of
execve_loadvm, were introduced with the PaX ASLR changes back in 2007
in order to pass the true stack base via AT_STACKBASE in the ELF
auxv, and in order to have getcontext() return the true stack base,
in the face of address space layout randomization.

This change, however, broke the stack base returned by getcontext()
in programs that have tried to exec other programs and failed in
various ways.  And made the later introduction of posix_spawn break
the stack base in the _parent_.

To fix this, we set p_stackbase -- under p_lock, to avoid racing with
sysctl_doeproc in another thread -- only in execve_runproc once we're
committed to the exec, but before copyoutargs -> es_copyargs =
elf_copyargs -> elf_populate_auxv needs to read it.  (That said,
elf_populate_auxv(..., pack, ...) could just use pack->es_minsaddr
directly anyway, and then we wouldn't have that ordering constraint.)

PR kern/60653: posix_spawn(3) causes incorrect stack base information

fork(2), vfork(2): Copy the parent's stack base pointer to the child.

Don't just leak whatever random stack pointer some recycled struct
proc had!

TBD: Move p_stackbase in struct proc so this is covered by the memcpy
above, in a separate commit so we can pull this one up without any
change to the layout of struct proc.
PR kern/60653: posix_spawn(3) causes incorrect stack base information

compat32: Advertise true stack base to getcontext(2).
Needs adjustment for PaX ASLR.

This was missed as part of:
Module Name:    src
Committed By:   christos
Date:           Wed Dec 26 22:11:54 UTC 2007
Add PaX ASLR (Address Space Layout Randomization) [from elad and myself]
https://mail-index.NetBSD.org/source-changes/2007/12/26/msg195243.html

PR kern/60877: t_signal_and_sp test failure with i386 userland on amd64
kernel


To generate a diff of this commit:
cvs rdiff -u -r1.53.4.1 -r1.53.4.2 src/sys/compat/netbsd32/netbsd32_signal.c
cvs rdiff -u -r1.83 -r1.83.14.1 src/sys/kern/exec_script.c
cvs rdiff -u -r1.84.20.2 -r1.84.20.3 src/sys/kern/exec_subr.c
cvs rdiff -u -r1.518.4.4 -r1.518.4.5 src/sys/kern/kern_exec.c
cvs rdiff -u -r1.229 -r1.229.4.1 src/sys/kern/kern_fork.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.