borg crashing my system - why does it open "dev/..." files ?

[devZer0]

i found that my virtual backup machine constantly crashed when running borg 1.1.0. no problems with 1.0.11

despite the fact that it´s weird that "head -n0 /dev/hpet" is crashing my virtual xenserver backup VM - i wonder why borg 1.1.0 does open() on device files at all while borg 1.0.11 doesn`t - and while rsync can handle and transfer that without a problem ( i rsync different VMs to centralized location and do borg backup from there - including /dev directory)

no problem:

# strace -f ./borg_1.0.11_backup.sh 2>&1 |grep "dev/hpet"
[pid  1727] lstat("dev/hpet", {st_mode=S_IFCHR|0600, st_rdev=makedev(10, 228), ...}) = 0
[pid  1727] llistxattr("dev/hpet", "", 4096) = 0
[pid  1727] getxattr("dev/hpet", "system.posix_acl_access", NULL, 0) = -1 ENODATA (No data available)
[pid  1727] getxattr("dev/hpet", "system.posix_acl_default", NULL, 0) = -1 ENODATA (No data available)

borg 1.1.0 crashing my machine:

# strace -f ./borg_1.1.0_backup.sh 2>&1 |grep "dev/hpet"
[pid  1945] lstat("dev/hpet", {st_mode=S_IFCHR|0600, st_rdev=makedev(10, 228), ...}) = 0
packet_write_wait: Connection to backupvm2 port 22: Broken pipe

repro-case:

# head -n0 /dev/hpet
<crash>

let´s have a look what it`s doing on other device files which do not crash machine on open():

# strace -f ./borg_1.1.0_one.sh 2>&1 |grep "dev/fuse"
[pid  1552] lstat("dev/fuse", {st_mode=S_IFCHR|0666, st_rdev=makedev(10, 229), ...}) = 0
[pid  1552] open("dev/fuse", O_RDONLY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC) = 5
[pid  1552] llistxattr("dev/fuse", "", 4096) = 0
[pid  1552] open("dev/fuse", O_RDONLY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC) = 5
[pid  1552] getxattr("dev/fuse", "system.posix_acl_access", NULL, 0) = -1 ENODATA (No data available)
[pid  1552] getxattr("dev/fuse", "system.posix_acl_default", NULL, 0) = -1 ENODATA (No data available)

[ThomasWaldmann]

duplicate of #3130

[ThomasWaldmann]

It's a bit strange though that opening some dev files is enough to crash a machine.
borg does not even read from the open file, it just does some ioctl and closes it again.

[enkore]

Just opening /dev/hpet crashing the machine is probably a Linux kernel bug. On my system the file has group perms for the "audio" group, so this might be a denial of service on some systems.

[devZer0]

yes, i think it's a xenserver bug, i opened https://bugs.xenserver.org/plugins/servlet/mobile#issue/XSO-809

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Gesendet: Samstag, 14. Oktober 2017 um 13:58 Uhr Von: TW ***@***.***> An: borgbackup/borg ***@***.***> Cc: devZer0 ***@***.***>, Author ***@***.***> Betreff: Re: [borgbackup/borg] borg crashing my system - why does it open "dev/..." files ? (#3159) It's a bit strange though that opening some dev files is enough to crash a machine. borg does not even read from the open file, it just does some ioctl and closes it again. -- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: #3159 (comment)