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| author | Vincent Fazio | 2021-01-31 07:19:30 +0100 |
|---|---|---|
| committer | Laurent Vivier | 2021-03-13 10:45:11 +0100 |
| commit | 934eed517857ce2de9a8a92c2599612581b4eb4a (patch) | |
| tree | 4028efe6c535db9e52466a1ee4702ad408031ff6 | |
| parent | linux-user/elfload: munmap proper address in pgd_find_hole_fallback (diff) | |
| download | qemu-934eed517857ce2de9a8a92c2599612581b4eb4a.tar.gz qemu-934eed517857ce2de9a8a92c2599612581b4eb4a.tar.xz qemu-934eed517857ce2de9a8a92c2599612581b4eb4a.zip | |
linux-user/elfload: do not assume MAP_FIXED_NOREPLACE kernel support
Previously, pgd_find_hole_fallback assumed that if the build host's libc
had MAP_FIXED_NOREPLACE defined that the address returned by mmap would
match the requested address. This is not a safe assumption for Linux
kernels prior to 4.17
Now, we always compare mmap's resultant address with the requested
address and no longer short-circuit based on MAP_FIXED_NOREPLACE.
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: <20210131061930.14554-1-vfazio@xes-inc.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
| -rw-r--r-- | linux-user/elfload.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 174ee7bad6..e525901659 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -2210,8 +2210,7 @@ static uintptr_t pgd_find_hole_fallback(uintptr_t guest_size, uintptr_t brk, PROT_NONE, flags, -1, 0); if (mmap_start != MAP_FAILED) { munmap(mmap_start, guest_size); - if (MAP_FIXED_NOREPLACE != 0 || - mmap_start == (void *) align_start) { + if (mmap_start == (void *) align_start) { return (uintptr_t) mmap_start + offset; } } |