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uml: don't kill pid 0 

A bit of defensive programming - during development, it ocassionally
happens that a call to init_new_context is missed, resulting in
context holding a host pid of zero.  When that address space is torn
down, destroy_context does a kill(0), which instantly kills the whole
UML without any errors whatsoever.

This patch add a check for pids less than 2, to also catch 1 and
negative pids.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jeff Dike 2008-02-04 22:31:10 -08:00 committed by Linus Torvalds
parent 1aa351a308
commit 00a905e614
1 changed files with 13 additions and 1 deletions
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14
arch/um/kernel/skas/mmu.c
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@ -164,8 +164,20 @@ void destroy_context(struct mm_struct *mm)
if (proc_mm) if (proc_mm)
os_close_file(mmu->id.u.mm_fd); os_close_file(mmu->id.u.mm_fd);
else else {
/*
* If init_new_context wasn't called, this will be
* zero, resulting in a kill(0), which will result in the
* whole UML suddenly dying. Also, cover negative and
* 1 cases, since they shouldn't happen either.
*/
if (mmu->id.u.pid < 2) {
printk(KERN_ERR "corrupt mm_context - pid = %d\n",
mmu->id.u.pid);
return;
}
os_kill_ptraced_process(mmu->id.u.pid, 1); os_kill_ptraced_process(mmu->id.u.pid, 1);
}
if (skas_needs_stub) if (skas_needs_stub)
free_page(mmu->id.stack); free_page(mmu->id.stack);