diff options
| author | Luke Shumaker <lukeshu@parabola.nu> | 2017-12-28 13:08:07 -0500 |
|---|---|---|
| committer | Laurent Vivier <laurent@vivier.eu> | 2018-03-09 21:25:32 +0100 |
| commit | e7ea02e62a37ea94a2ee6cc99e7c682ef0e61e9f (patch) | |
| tree | 64cadb950f41b474733de2efb67b333f116735fc | |
| parent | f2024817548f9538cbe626f88ca9f37ff0f5d468 (diff) | |
linux-user: init_guest_space: Correctly handle guest_start in commpage initialization
init_guest_commpage needs to check if the mapped space, which ends at
real_start+real_size overlaps with where it needs to put the commpage,
which is (assuming sane qemu_host_page_size) guest_base + 0xffff000, where
guest_base is real_start - guest_start.
[guest_base][ 0xffff0000 ][commpage]
[guest_base][guest_start][real_size] [commpage]
[ real_start ][real_size] [commpage]
^
fail if this gap < 0
Since init_guest_commpage wants to do everything relative to guest_base
(rather than real_start), it obviously needs to be comparing 0xffff0000
against guest_start+real_size, not just real_size.
This bug has been present since 806d102141b99d4f1e55a97d68b7ea8c8ba3129f in
2012, but guest_start is usually 0, and prior to v2.11 real_size was
usually much smaller than 0xffff0000, so it was uncommon for it to have
made a difference.
Signed-off-by: Luke Shumaker <lukeshu@parabola.nu>
Message-Id: <20171228180814.9749-5-lukeshu@lukeshu.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
| -rw-r--r-- | linux-user/elfload.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/linux-user/elfload.c b/linux-user/elfload.c index dcdd756908..feecbd4163 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -1856,7 +1856,7 @@ unsigned long init_guest_space(unsigned long host_start, #if defined(TARGET_ARM) && !defined(TARGET_AARCH64) /* On 32-bit ARM, we need to also be able to map the commpage. */ int valid = init_guest_commpage(real_start - guest_start, - real_size); + real_size + guest_start); if (valid == 1) { break; } else if (valid == -1) { |