On Mon, 27 Jul 2020 at 13:24, Alex Bennée <[email protected]> wrote:
>
> Plain MAP_FIXED has the undesirable behaviour of splatting exiting
> maps so we don't actually achieve what we want when looking for gaps.
> We should be using MAP_FIXED_NOREPLACE. As this isn't always available
> we need to potentially check the returned address to see if the kernel
> gave us what we asked for.
>
> Fixes: ad592e37dfc ("linux-user: provide fallback pgd_find_hole for bare
> chroots")
> Signed-off-by: Alex Bennée <[email protected]>
> Reviewed-by: Richard Henderson <[email protected]>
> Message-Id: <[email protected]>
Hi; Coverity thinks this conditional expression is suspicious
(CID 1431059):
> if (mmap_start != MAP_FAILED) {
> munmap((void *) align_start, guest_size);
> - return (uintptr_t) mmap_start + offset;
> + if (MAP_FIXED_NOREPLACE || mmap_start == (void *)
> align_start) {
because it's performing a logical OR operation where the left
operand is an integer constant that's neither 0 nor 1
(it's 1048576). What was this intended to be?
> + return (uintptr_t) mmap_start + offset;
> + }
> }
thanks
-- PMM
