While pgd_find_hole_fallback returns the beginning of the hole found, pgb_find_hole returns guest_base, which is somewhat different as the binary qemu-user is loading usually have non-zero load address.
Failing to take that into account leads to random crashes if the hole is "just big enough", but not bigger: in that case, important mappings (e.g. parts of qemu-user itself) may be replaced with the binary we are loading (e.g. guest elf interpreter). Downstream issue (in Russian): https://bugzilla.altlinux.org/39141 Signed-off-by: Ivan A. Melnikov <i...@altlinux.org> --- linux-user/elfload.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/linux-user/elfload.c b/linux-user/elfload.c index bab4237e90..58281e00f8 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -2259,7 +2259,8 @@ static uintptr_t pgb_find_hole(uintptr_t guest_loaddr, uintptr_t guest_size, brk = (uintptr_t)sbrk(0); if (!maps) { - return pgd_find_hole_fallback(guest_size, brk, align, offset); + ret = pgd_find_hole_fallback(guest_size, brk, align, offset); + return (ret == (uintptr_t) -1) ? -1 : (ret - guest_loaddr); } /* The first hole is before the first map entry. */ -- 2.29.2
