diff options
| author | Jonathan Marler <johnnymarler@gmail.com> | 2020-05-02 10:12:25 -0600 |
|---|---|---|
| committer | Laurent Vivier <laurent@vivier.eu> | 2020-06-05 21:23:22 +0200 |
| commit | 257a7e212d5e518ac53bd6a02a3157cf4594c8b3 (patch) | |
| tree | 0ae92131a977d26170d8f2f1f3ab2ab856528c29 | |
| parent | fd568660b7ae9b9e45cbb616acc91ae4c065c32d (diff) | |
linux-user/mmap.c: fix integer underflow in target_mremap
Fixes: https://bugs.launchpad.net/bugs/1876373
This code path in mmap occurs when a page size is decreased with mremap. When a section of pages is shrunk, qemu calls mmap_reserve on the pages that were released. However, it has the diff operation reversed, subtracting the larger old_size from the smaller new_size. Instead, it should be subtracting the smaller new_size from the larger old_size. You can also see in the previous line of the change that this mmap_reserve call only occurs when old_size > new_size.
Bug: https://bugs.launchpad.net/qemu/+bug/1876373
Signed-off-by: Jonathan Marler <johnnymarler@gmail.com>
Reviewded-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20200502161225.14346-1-johnnymarler@gmail.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
| -rw-r--r-- | linux-user/mmap.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/linux-user/mmap.c b/linux-user/mmap.c index e378033797..caab62909e 100644 --- a/linux-user/mmap.c +++ b/linux-user/mmap.c @@ -708,7 +708,7 @@ abi_long target_mremap(abi_ulong old_addr, abi_ulong old_size, if (prot == 0) { host_addr = mremap(g2h(old_addr), old_size, new_size, flags); if (host_addr != MAP_FAILED && reserved_va && old_size > new_size) { - mmap_reserve(old_addr + old_size, new_size - old_size); + mmap_reserve(old_addr + old_size, old_size - new_size); } } else { errno = ENOMEM; |