conditionally reschedule in mls_convert_context while loading selinux policy.
PATCH 1/2 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..
Quoted 21 lines
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
Quoted 8 lines
[<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:
Quoted 2 lines
Maybe put a
cond_resched()within theebitmap_for_each_positive_bit()loop inmls_convert_context()?
That seems to do the trick. Tested by downgrading and re-upgrading selinux-policy-targeted.
Signed-off-by Dave Jones <[email protected]>
--- security/selinux/ss/mls.c | 2 ++ 1 file changed, 2 insertions(+)
security/selinux/ss/mls.c +2 -0
@@ -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;
Signature · 1 line
1.9.0
Quoted 36 lines · Dave Jones
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..
Quoted 21 lines
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+0x68/0xb0Quoted 8 lines
[<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
Quoted 8 lines
Stephen Smalley suggested:
Quoted 2 lines
Maybe put a
cond_resched()within theebitmap_for_each_positive_bit()loop inmls_convert_context()?That seems to do the trick. Tested by downgrading and re-upgrading selinux-policy-targeted.
Signed-off-by Dave Jones <[email protected]>
Acked-by Stephen Smalley <[email protected]>
Quoted 19 lines
--- security/selinux/ss/mls.c | 2 ++ 1 file changed, 2 insertions(+)security/selinux/ss/mls.c +2
-0@@ -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;
Paul Moore
AppliedQuoted 41 lines · Dave Jones
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..
Quoted 22 lines
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+0x68/0xb0Quoted 8 lines
[<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/0xe2Stephen Smalley suggested:
Quoted 2 lines
Maybe put a
cond_resched()within theebitmap_for_each_positive_bit()loop inmls_convert_context()?
Quoted 8 lines
That seems to do the trick. Tested by downgrading and re-upgrading selinux-policy-targeted.
Signed-off-by Dave Jones <[email protected]>--- security/selinux/ss/mls.c | 2 ++ 1 file changed, 2 insertions(+)
Merged to the SELinux #next branch, thanks.
Quoted 13 lines
security/selinux/ss/mls.c +2
-0@@ -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;
Signature · 2 lines
paul moore security and virtualization @ redhat