Re: [PATCH] mm/mmap: Fix error return in do_vmi_align_munmap()

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Jun 28, 2023 at 11:42:45AM +0100, David Woodhouse wrote:
> From: David Woodhouse <dwmw@amazon.co.uk>
> 
> 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: 606c812eb1d5 ("mm/mmap: Fix error path in do_vmi_align_munmap()")
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> ---
>  mm/mmap.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>