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[PATCH v2] linux-user: Adjust pgd_find_hole_fallback result with guest_l
From: |
Ivan A. Melnikov |
Subject: |
[PATCH v2] linux-user: Adjust pgd_find_hole_fallback result with guest_loaddr |
Date: |
Sat, 6 Mar 2021 13:33:00 +0400 |
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 <iv@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