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[PULL 3/5] linux-user/elfload: munmap proper address in pgd_find_hole_fa
From: |
Laurent Vivier |
Subject: |
[PULL 3/5] linux-user/elfload: munmap proper address in pgd_find_hole_fallback |
Date: |
Sat, 13 Mar 2021 10:47:45 +0100 |
From: Vincent Fazio <vfazio@gmail.com>
Previously, if the build host's libc did not define MAP_FIXED_NOREPLACE
or if the running kernel didn't support that flag, it was possible for
pgd_find_hole_fallback to munmap an incorrect address which could lead to
SIGSEGV if the range happened to overlap with the mapped address of the
QEMU binary.
mmap(0x1000, 22261224, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE,
-1, 0) = 0x7f889d331000
munmap(0x1000, 22261224) = 0
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x84b817} ---
++ killed by SIGSEGV +++
Now, always munmap the address returned by mmap.
Fixes: 2667e069e7b5 ("linux-user: don't use MAP_FIXED in
pgd_find_hole_fallback")
Signed-off-by: Vincent Fazio <vfazio@gmail.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20210131061849.12615-1-vfazio@xes-inc.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
linux-user/elfload.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 140a9716324d..174ee7bad677 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -2209,7 +2209,7 @@ static uintptr_t pgd_find_hole_fallback(uintptr_t
guest_size, uintptr_t brk,
void * mmap_start = mmap((void *) align_start, guest_size,
PROT_NONE, flags, -1, 0);
if (mmap_start != MAP_FAILED) {
- munmap((void *) align_start, guest_size);
+ munmap(mmap_start, guest_size);
if (MAP_FIXED_NOREPLACE != 0 ||
mmap_start == (void *) align_start) {
return (uintptr_t) mmap_start + offset;
--
2.29.2
- [PULL 0/5] Linux user for 6.0 patches, Laurent Vivier, 2021/03/13
- [PULL 4/5] linux-user/elfload: do not assume MAP_FIXED_NOREPLACE kernel support, Laurent Vivier, 2021/03/13
- [PULL 1/5] linux-user: Fix executable page of /proc/self/maps, Laurent Vivier, 2021/03/13
- [PULL 3/5] linux-user/elfload: munmap proper address in pgd_find_hole_fallback,
Laurent Vivier <=
- [PULL 2/5] linux-user: manage binfmt-misc preserve-arg[0] flag, Laurent Vivier, 2021/03/13
- [PULL 5/5] linux-user/elfload: fix address calculation in fallback scenario, Laurent Vivier, 2021/03/13
- Re: [PULL 0/5] Linux user for 6.0 patches, no-reply, 2021/03/13
- Re: [PULL 0/5] Linux user for 6.0 patches, Peter Maydell, 2021/03/14