From: Jonathan Marler <johnnymar...@gmail.com> 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 <johnnymar...@gmail.com> Reviewded-by: Laurent Vivier <laur...@vivier.eu> Message-Id: <20200502161225.14346-1-johnnymar...@gmail.com> Signed-off-by: Laurent Vivier <laur...@vivier.eu> --- linux-user/mmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/linux-user/mmap.c b/linux-user/mmap.c index e37803379747..caab62909eb1 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; -- 2.26.2