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| author | Dave Jones <davej@redhat.com> | 2014-05-15 15:02:53 -0400 |
|---|---|---|
| committer | Serge Hallyn <serge.hallyn@ubuntu.com> | 2014-06-03 14:21:49 -0500 |
| commit | 9a591f39a9d11df435652738e7f6e62a09c87909 (patch) | |
| tree | 8bfeb0efdb3936c92d00129db15370aacff2971e | |
| parent | 5b589d44fad18228f18749360d008d5c8ff3aaf8 (diff) | |
| download | lwn-9a591f39a9d11df435652738e7f6e62a09c87909.tar.gz lwn-9a591f39a9d11df435652738e7f6e62a09c87909.zip | |
selinux: conditionally reschedule in mls_convert_context while loading selinux policy
On a slow machine (with debugging enabled), upgrading selinux policy may take
a considerable amount of time. Long enough that the softlockup detector
gets triggered.
The backtrace looks like this..
> BUG: soft lockup - CPU#2 stuck for 23s! [load_policy:19045]
> Call Trace:
> [<ffffffff81221ddf>] symcmp+0xf/0x20
> [<ffffffff81221c27>] hashtab_search+0x47/0x80
> [<ffffffff8122e96c>] mls_convert_context+0xdc/0x1c0
> [<ffffffff812294e8>] convert_context+0x378/0x460
> [<ffffffff81229170>] ? security_context_to_sid_core+0x240/0x240
> [<ffffffff812221b5>] sidtab_map+0x45/0x80
> [<ffffffff8122bb9f>] security_load_policy+0x3ff/0x580
> [<ffffffff810788a8>] ? sched_clock_cpu+0xa8/0x100
> [<ffffffff810786dd>] ? sched_clock_local+0x1d/0x80
> [<ffffffff810788a8>] ? sched_clock_cpu+0xa8/0x100
> [<ffffffff8103096a>] ? __change_page_attr_set_clr+0x82a/0xa50
> [<ffffffff810786dd>] ? sched_clock_local+0x1d/0x80
> [<ffffffff810788a8>] ? sched_clock_cpu+0xa8/0x100
> [<ffffffff8103096a>] ? __change_page_attr_set_clr+0x82a/0xa50
> [<ffffffff810788a8>] ? sched_clock_cpu+0xa8/0x100
> [<ffffffff81534ddc>] ? retint_restore_args+0xe/0xe
> [<ffffffff8109c82d>] ? trace_hardirqs_on_caller+0xfd/0x1c0
> [<ffffffff81279a2e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
> [<ffffffff810d28a8>] ? rcu_irq_exit+0x68/0xb0
> [<ffffffff81534ddc>] ? retint_restore_args+0xe/0xe
> [<ffffffff8121e947>] sel_write_load+0xa7/0x770
> [<ffffffff81139633>] ? vfs_write+0x1c3/0x200
> [<ffffffff81210e8e>] ? security_file_permission+0x1e/0xa0
> [<ffffffff8113952b>] vfs_write+0xbb/0x200
> [<ffffffff811581c7>] ? fget_light+0x397/0x4b0
> [<ffffffff81139c27>] SyS_write+0x47/0xa0
> [<ffffffff8153bde4>] tracesys+0xdd/0xe2
Stephen Smalley suggested:
> Maybe put a cond_resched() within the ebitmap_for_each_positive_bit()
> loop in mls_convert_context()?
That seems to do the trick. Tested by downgrading and re-upgrading selinux-policy-targeted.
Signed-off-by: Dave Jones <davej@redhat.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <pmoore@redhat.com>
| -rw-r--r-- | security/selinux/ss/mls.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/security/selinux/ss/mls.c b/security/selinux/ss/mls.c index c85bc1ec040c..d307b37ddc2b 100644 --- a/security/selinux/ss/mls.c +++ b/security/selinux/ss/mls.c @@ -492,6 +492,8 @@ int mls_convert_context(struct policydb *oldp, rc = ebitmap_set_bit(&bitmap, catdatum->value - 1, 1); if (rc) return rc; + + cond_resched(); } ebitmap_destroy(&c->range.level[l].cat); c->range.level[l].cat = bitmap; |