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seccomp: don't block getters for resource control syscalls

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Recent GLibC calls sched_getaffinity in code paths related to malloc and
when QEMU blocks access, it sends it off into a bad codepath resulting
in stack exhaustion[1]. The GLibC bug is being fixed[2], but none the
less, GLibC has valid reasons to want to use sched_getaffinity.

It is not unreasonable for code to want to run many resource syscalls
for information gathering, so it is a bit too harsh for QEMU to block
them.

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1975693
[2] https://sourceware.org/pipermail/libc-alpha/2021-June/128271.html
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Acked-by: Eduardo Otubo <otubo@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrangé 2021-06-30 15:19:38 +01:00
parent cfb47f2178
commit 2ce949a4c1
1 changed files with 0 additions and 6 deletions
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6
softmmu/qemu-seccomp.c
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@ -97,17 +97,11 @@ static const struct QemuSeccompSyscall denylist[] = {
{ SCMP_SYS(vfork), QEMU_SECCOMP_SET_SPAWN },
{ SCMP_SYS(execve), QEMU_SECCOMP_SET_SPAWN },
/* resource control */
{ SCMP_SYS(getpriority), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(setpriority), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_setparam), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_getparam), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_setscheduler), QEMU_SECCOMP_SET_RESOURCECTL,
ARRAY_SIZE(sched_setscheduler_arg), sched_setscheduler_arg },
{ SCMP_SYS(sched_getscheduler), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_setaffinity), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_getaffinity), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_get_priority_max), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_get_priority_min), QEMU_SECCOMP_SET_RESOURCECTL },
};
static inline __attribute__((unused)) int