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s390 updates for 6.0-rc3

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- Fix double free of guarded storage and runtime instrumentation control
   blocks on fork() failure.
 
 - Fix triggering write fault when VMA does not allow VM_WRITE.
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Merge tag 's390-6.0-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

Pull s390 fixes from Vasily Gorbik:

 - Fix double free of guarded storage and runtime instrumentation
   control blocks on fork() failure

 - Fix triggering write fault when VMA does not allow VM_WRITE

* tag 's390-6.0-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/mm: do not trigger write fault when vma does not allow VM_WRITE
  s390: fix double free of GS and RI CBs on fork() failure
This commit is contained in:
Linus Torvalds 2022-08-27 15:40:51 -07:00
commit dee1873796
2 changed files with 19 additions and 7 deletions
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22
arch/s390/kernel/process.c
View file

@ -91,6 +91,18 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
memcpy(dst, src, arch_task_struct_size);
dst->thread.fpu.regs = dst->thread.fpu.fprs;
/*
* Don't transfer over the runtime instrumentation or the guarded
* storage control block pointers. These fields are cleared here instead
* of in copy_thread() to avoid premature freeing of associated memory
* on fork() failure. Wait to clear the RI flag because ->stack still
* refers to the source thread.
*/
dst->thread.ri_cb = NULL;
dst->thread.gs_cb = NULL;
dst->thread.gs_bc_cb = NULL;
return 0;
}
@ -150,13 +162,11 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
frame->childregs.flags = 0;
if (new_stackp)
frame->childregs.gprs[15] = new_stackp;
/* Don't copy runtime instrumentation info */
p->thread.ri_cb = NULL;
/*
* Clear the runtime instrumentation flag after the above childregs
* copy. The CB pointer was already cleared in arch_dup_task_struct().
*/
frame->childregs.psw.mask &= ~PSW_MASK_RI;
/* Don't copy guarded storage control block */
p->thread.gs_cb = NULL;
p->thread.gs_bc_cb = NULL;
/* Set a new TLS ? */
if (clone_flags & CLONE_SETTLS) {

4
arch/s390/mm/fault.c
View file

@ -379,7 +379,9 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
flags = FAULT_FLAG_DEFAULT;
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
if (access == VM_WRITE || is_write)
if (is_write)
access = VM_WRITE;
if (access == VM_WRITE)
flags |= FAULT_FLAG_WRITE;
mmap_read_lock(mm);