** Changed in: linux (Ubuntu)
Status: Confirmed => Invalid
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https://bugs.launchpad.net/bugs/1799237
Title:
mprotect fails on ext4 with dax
Status in Ubuntu:
Invalid
Status in linux package in Ubuntu:
Invalid
Status in pmdk package in Ubuntu:
Invalid
Status in linux source package in Bionic:
Fix Committed
Bug description:
I have a file located on ext4 mounted with "dax". When I call mmap on that
file with protection flag different than PROT_NONE and pass the returned
address to mprotect(..., PROT_NONE) it fails with:
mprotect: Permission denied
This bug affects PMDK (https://github.com/pmem/pmdk) and seems to be Ubuntu
kernel-specific.
Problem was observer on kernel 4.15.0-36-generic and 4.15.0-34-generic
Below is a code which can be used to reproduce the issue.
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
int main(int argc, char *argv[])
{
if (argc < 3) {
fprintf(stderr, "usage %s file size\n",
argv[0]);
return 1;
}
int size = atoi(argv[2]);
int fd = open(argv[1], O_RDWR);
if (fd < 0) {
perror("open");
return 1;
}
void *addr = mmap(NULL, size, PROT_READ | PROT_WRITE,
MAP_SHARED, fd, 0);
if (addr == MAP_FAILED) {
perror("mmap");
return 1;
}
if(mprotect(addr, size, PROT_NONE)) {
perror("mprotect");
return 1;
}
return 0;
}
---
ProblemType: Bug
ApportVersion: 2.20.9-0ubuntu7.4
Architecture: amd64
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq',
'/dev/snd/timer'] failed with exit code 1:
CRDA: Error: command ['iw', 'reg', 'get'] failed with exit code 1: nl80211
not found.
CurrentDesktop: ubuntu:GNOME
DistroRelease: Ubuntu 18.04
InstallationDate: Installed on 2018-10-23 (0 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64
(20180725)
IwConfig:
lo no wireless extensions.
enp0s3 no wireless extensions.
Lsusb:
Bus 001 Device 002: ID 80ee:0021 VirtualBox USB Tablet
Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
MachineType: innotek GmbH VirtualBox
Package: linux (not installed)
ProcFB:
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-36-generic
root=UUID=48e87c4c-3028-4252-b7bb-e1e6091ff7f6 ro quiet splash
ProcVersionSignature: Ubuntu 4.15.0-36.39-generic 4.15.18
RelatedPackageVersions:
linux-restricted-modules-4.15.0-36-generic N/A
linux-backports-modules-4.15.0-36-generic N/A
linux-firmware 1.173.1
RfKill:
Tags: bionic
Uname: Linux 4.15.0-36-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 12/01/2006
dmi.bios.vendor: innotek GmbH
dmi.bios.version: VirtualBox
dmi.board.name: VirtualBox
dmi.board.vendor: Oracle Corporation
dmi.board.version: 1.2
dmi.chassis.type: 1
dmi.chassis.vendor: Oracle Corporation
dmi.modalias:
dmi:bvninnotekGmbH:bvrVirtualBox:bd12/01/2006:svninnotekGmbH:pnVirtualBox:pvr1.2:rvnOracleCorporation:rnVirtualBox:rvr1.2:cvnOracleCorporation:ct1:cvr:
dmi.product.family: Virtual Machine
dmi.product.name: VirtualBox
dmi.product.version: 1.2
dmi.sys.vendor: innotek GmbH
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