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mm/mmap: Fix error return in do_vmi_align_munmap()

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commit 6c26bd4384 upstream,

If mas_store_gfp() in the gather loop failed, the 'error' variable that
ultimately gets returned was not being set. In many cases, its original
value of -ENOMEM was still in place, and that was fine. But if VMAs had
been split at the start or end of the range, then 'error' could be zero.

Change to the 'error = foo(); if (error) goto …' idiom to fix the bug.

Also clean up a later case which avoided the same bug by *explicitly*
setting error = -ENOMEM right before calling the function that might
return -ENOMEM.

In a final cosmetic change, move the 'Point of no return' comment to
*after* the goto. That's been in the wrong place since the preallocation
was removed, and this new error path was added.

Fixes: 606c812eb1 ("mm/mmap: Fix error path in do_vmi_align_munmap()")
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Cc: stable@vger.kernel.org
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
David Woodhouse 2023-06-28 10:55:03 +01:00 committed by Greg Kroah-Hartman
parent a149174ff8
commit 42a018a796
1 changed files with 3 additions and 1 deletions
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4
mm/mmap.c
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@ -2404,7 +2404,8 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma,
break;
}
mas_set_range(&mas_detach, next->vm_start, next->vm_end - 1);
if (mas_store_gfp(&mas_detach, next, GFP_KERNEL))
error = mas_store_gfp(&mas_detach, next, GFP_KERNEL);
if (error)
goto munmap_gather_failed;
if (next->vm_flags & VM_LOCKED)
locked_vm += vma_pages(next);
@ -2456,6 +2457,7 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma,
mas_set_range(mas, start, end - 1);
}
#endif
/* Point of no return */
mas_store_prealloc(mas, NULL);
mm->locked_vm -= locked_vm;