Following
https://wiki.qemu.org/Contribute/SubmitAPatch#Make_code_motion_patches_easy_to_review:
@@ -1,5 +1,5 @@
---
--- a/linux-user/mmap.c
- if (len == 0)
- goto the_end;
--
+++ b/linux-user/mmap.c
+ if (len == 0) {
+ errno = EINVAL;
+ goto fail;
+ }
--
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https://bugs.launchpad.net/bugs/1783362
Title:
qemu-user: mmap should return failure (MAP_FAILED, -1) instead of
success (NULL, 0) when len==0
Status in QEMU:
New
Status in qemu package in Ubuntu:
New
Bug description:
As shown in https://github.com/beehive-
lab/mambo/issues/19#issuecomment-407420602, with len==0 mmap returns
success (NULL, 0) instead of failure (MAP_FAILED, -1) in a x86_64 host
executing a ELF 64-bit LSB executable, ARM aarch64 binary.
Steps to reproduce the bug:
- (cross-)compile the attached source file:
$ aarch64-linux-gnu-gcc -static -std=gnu99 -lpthread test/mmap_qemu.c
-o mmap_qemu
- Execute in a x86_64 host with qemu-user and qemu-user-binfmt:
$ ./mmap_qemu
alloc: 0
MAP_FAILED: -1
errno: 0
mmap_qemu: test/mmap_qemu.c:15: main: Assertion `alloc == MAP_FAILED' failed.
qemu: uncaught target signal 6 (Aborted) - core dumped
Aborted (core dumped)
- Execute in a ARM host without any additional dependecy:
$ ./mmap_qemu
alloc: -1
MAP_FAILED: -1
errno: 22
The bug is present in Fedora:
$ qemu-aarch64 --version
qemu-aarch64 version 2.11.2(qemu-2.11.2-1.fc28)
Copyright (c) 2003-2017 Fabrice Bellard and the QEMU Project developers
$ uname -r
4.17.7-200.fc28.x86_64
And also in Ubuntu:
$ qemu-aarch64 --version
qemu-aarch64 version 2.12.0 (Debian 1:2.12+dfsg-3ubuntu3)
Copyright (c) 2003-2017 Fabrice Bellard and the QEMU Project developers
$ uname -r
4.15.0-23-generic
Possibly related to:
- https://lists.freebsd.org/pipermail/freebsd-hackers/2009-July/029109.html
- https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=203852
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