Public bug reported:
QEMU version: latest master (fcea73709b966a7ded9efa7b106ea50c7fe9025c)
OS version: Ubuntu 14.04.5
Configured with: ../configure --target-list=x86_64-linux-user
QEMU Linux usermode emulation does not handle write() syscalls with zero
length and a null pointer correctly: on Linux this returns 0, but in
emulation this returns -1.
I ran into this while using an aarch64 abuild-tar from Alpine Linux in
user-mode emulation; here's the minimized reproduction test case:
zhuowei@zhuowei-tablet:/tmp$ cat writezerobytes.c
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
int main() {
ssize_t ret = write(STDOUT_FILENO, NULL, 0);
fprintf(stderr, "write returned %ld\n", ret);
return 0;
}
zhuowei@zhuowei-tablet:/tmp$ gcc -o writezerobytes writezerobytes.c
zhuowei@zhuowei-tablet:/tmp$ uname -a
Linux zhuowei-tablet 3.13.0-129-generic #178-Ubuntu SMP Fri Aug 11 12:48:20 UTC
2017 x86_64 x86_64 x86_64 GNU/Linux
zhuowei@zhuowei-tablet:/tmp$ ./writezerobytes
write returned 0
zhuowei@zhuowei-tablet:/tmp$
/media/zhuowei/redhd/docs/repos/qemu/build4/x86_64-linux-user/qemu-x86_64
./writezerobytes
write returned -1
zhuowei@zhuowei-tablet:/tmp$
/media/zhuowei/redhd/docs/repos/qemu/build4/x86_64-linux-user/qemu-x86_64
--version
qemu-x86_64 version 2.10.50 (v2.10.0-471-gfcea737-dirty)
Copyright (c) 2003-2017 Fabrice Bellard and the QEMU Project developers
** Affects: qemu
Importance: Undecided
Status: New
** Description changed:
QEMU version: latest master (fcea73709b966a7ded9efa7b106ea50c7fe9025c)
- OS version: Ubuntu 14.04.3
+ OS version: Ubuntu 14.04.5
Configured with: ../configure --target-list=x86_64-linux-user
QEMU Linux usermode emulation does not handle write() syscalls with zero
length and a null pointer correctly: on Linux this returns 0, but in
emulation this returns -1.
I ran into this while using an aarch64 abuild-tar from Alpine Linux in
user-mode emulation; here's the minimized reproduction test case:
zhuowei@zhuowei-tablet:/tmp$ cat writezerobytes.c
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
int main() {
- ssize_t ret = write(STDOUT_FILENO, NULL, 0);
- fprintf(stderr, "write returned %ld\n", ret);
- return 0;
+ ssize_t ret = write(STDOUT_FILENO, NULL, 0);
+ fprintf(stderr, "write returned %ld\n", ret);
+ return 0;
}
zhuowei@zhuowei-tablet:/tmp$ gcc -o writezerobytes writezerobytes.c
zhuowei@zhuowei-tablet:/tmp$ uname -a
Linux zhuowei-tablet 3.13.0-129-generic #178-Ubuntu SMP Fri Aug 11 12:48:20
UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
- zhuowei@zhuowei-tablet:/tmp$ ./writezerobytes
- write returned 0
+ zhuowei@zhuowei-tablet:/tmp$ ./writezerobytes
+ write returned 0
zhuowei@zhuowei-tablet:/tmp$
/media/zhuowei/redhd/docs/repos/qemu/build4/x86_64-linux-user/qemu-x86_64
./writezerobytes
write returned -1
zhuowei@zhuowei-tablet:/tmp$
/media/zhuowei/redhd/docs/repos/qemu/build4/x86_64-linux-user/qemu-x86_64
--version
qemu-x86_64 version 2.10.50 (v2.10.0-471-gfcea737-dirty)
Copyright (c) 2003-2017 Fabrice Bellard and the QEMU Project developers
--
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https://bugs.launchpad.net/bugs/1716292
Title:
User mode emulation returns wrong value for write(fd, NULL, 0)
Status in QEMU:
New
Bug description:
QEMU version: latest master (fcea73709b966a7ded9efa7b106ea50c7fe9025c)
OS version: Ubuntu 14.04.5
Configured with: ../configure --target-list=x86_64-linux-user
QEMU Linux usermode emulation does not handle write() syscalls with
zero length and a null pointer correctly: on Linux this returns 0, but
in emulation this returns -1.
I ran into this while using an aarch64 abuild-tar from Alpine Linux in
user-mode emulation; here's the minimized reproduction test case:
zhuowei@zhuowei-tablet:/tmp$ cat writezerobytes.c
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
int main() {
ssize_t ret = write(STDOUT_FILENO, NULL, 0);
fprintf(stderr, "write returned %ld\n", ret);
return 0;
}
zhuowei@zhuowei-tablet:/tmp$ gcc -o writezerobytes writezerobytes.c
zhuowei@zhuowei-tablet:/tmp$ uname -a
Linux zhuowei-tablet 3.13.0-129-generic #178-Ubuntu SMP Fri Aug 11 12:48:20
UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
zhuowei@zhuowei-tablet:/tmp$ ./writezerobytes
write returned 0
zhuowei@zhuowei-tablet:/tmp$
/media/zhuowei/redhd/docs/repos/qemu/build4/x86_64-linux-user/qemu-x86_64
./writezerobytes
write returned -1
zhuowei@zhuowei-tablet:/tmp$
/media/zhuowei/redhd/docs/repos/qemu/build4/x86_64-linux-user/qemu-x86_64
--version
qemu-x86_64 version 2.10.50 (v2.10.0-471-gfcea737-dirty)
Copyright (c) 2003-2017 Fabrice Bellard and the QEMU Project developers
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