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authorDave Jones <davej@redhat.com>2014-05-15 15:02:53 -0400
committerSerge Hallyn <serge.hallyn@ubuntu.com>2014-06-03 14:21:49 -0500
commit9a591f39a9d11df435652738e7f6e62a09c87909 (patch)
tree8bfeb0efdb3936c92d00129db15370aacff2971e /security
parent5b589d44fad18228f18749360d008d5c8ff3aaf8 (diff)
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>
Diffstat (limited to 'security')
-rw-r--r--security/selinux/ss/mls.c2
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;

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