From: Michael Ellerman <mpe@ellerman.id.au> Date: 2018-10-19 06:01:27
Recently in commit 7241d26e8175 ("powerpc/64: properly initialise
the stackprotector canary on SMP.") we fixed a crash with stack
protector on SMP by initialising the stack canary in
cpu_idle_thread_init().
But this can also causes crashes, when a CPU comes back online after
being offline:
Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: pnv_smp_cpu_kill_self+0x2a0/0x2b0
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.19.0-rc3-gcc-7.3.1-00168-g4ffe713b7587 #94
Call Trace:
dump_stack+0xb0/0xf4 (unreliable)
panic+0x144/0x328
__stack_chk_fail+0x2c/0x30
pnv_smp_cpu_kill_self+0x2a0/0x2b0
cpu_die+0x48/0x70
arch_cpu_idle_dead+0x20/0x40
do_idle+0x274/0x390
cpu_startup_entry+0x38/0x50
start_secondary+0x5e4/0x600
start_secondary_prolog+0x10/0x14
Looking at the stack we see that the canary value in the stack frame
doesn't match the canary in the task/paca. That is because we have
reinitialised the task/paca value, but then the CPU coming online has
returned into a function using the old canary value. That causes the
comparison to fail.
Instead we can call boot_init_stack_canary() from start_secondary()
which never returns. This is essentially what the generic code does in
cpu_startup_entry() under #ifdef X86, we should make that non-x86
specific in a future patch.
Fixes: 7241d26e8175 ("powerpc/64: properly initialise the stackprotector canary on SMP.")
Reported-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
arch/powerpc/kernel/smp.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
@@ -1316,6 +1310,8 @@ void start_secondary(void *unused)notify_cpu_starting(cpu);set_cpu_online(cpu,true);+boot_init_stack_canary();+local_irq_enable();/* We can enable ftrace for secondary cpus now */
Recently in commit 7241d26e8175 ("powerpc/64: properly initialise
the stackprotector canary on SMP.") we fixed a crash with stack
protector on SMP by initialising the stack canary in
cpu_idle_thread_init().
But this can also causes crashes, when a CPU comes back online after
being offline:
Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: pnv_smp_cpu_kill_self+0x2a0/0x2b0
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.19.0-rc3-gcc-7.3.1-00168-g4ffe713b7587 #94
Call Trace:
dump_stack+0xb0/0xf4 (unreliable)
panic+0x144/0x328
__stack_chk_fail+0x2c/0x30
pnv_smp_cpu_kill_self+0x2a0/0x2b0
cpu_die+0x48/0x70
arch_cpu_idle_dead+0x20/0x40
do_idle+0x274/0x390
cpu_startup_entry+0x38/0x50
start_secondary+0x5e4/0x600
start_secondary_prolog+0x10/0x14
Looking at the stack we see that the canary value in the stack frame
doesn't match the canary in the task/paca. That is because we have
reinitialised the task/paca value, but then the CPU coming online has
returned into a function using the old canary value. That causes the
comparison to fail.
Instead we can call boot_init_stack_canary() from start_secondary()
which never returns. This is essentially what the generic code does in
cpu_startup_entry() under #ifdef X86, we should make that non-x86
specific in a future patch.
This shall not be done on arches that uses a global canary, so I think
it has to be kept arch specific. Indeed I think x86 should move it to
cpu_bringup_and_idle(). I'll propose them a patch for that.
Christophe
Fixes: 7241d26e8175 ("powerpc/64: properly initialise the stackprotector canary on SMP.")
Reported-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
@@ -1316,6 +1310,8 @@ void start_secondary(void *unused)notify_cpu_starting(cpu);set_cpu_online(cpu,true);+boot_init_stack_canary();+local_irq_enable();/* We can enable ftrace for secondary cpus now */
From: Michael Ellerman <mpe@ellerman.id.au> Date: 2018-10-21 08:39:19
Michael Ellerman [off-list ref] writes:
quoted hunk
Recently in commit 7241d26e8175 ("powerpc/64: properly initialise
the stackprotector canary on SMP.") we fixed a crash with stack
protector on SMP by initialising the stack canary in
cpu_idle_thread_init().
But this can also causes crashes, when a CPU comes back online after
being offline:
Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: pnv_smp_cpu_kill_self+0x2a0/0x2b0
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.19.0-rc3-gcc-7.3.1-00168-g4ffe713b7587 #94
Call Trace:
dump_stack+0xb0/0xf4 (unreliable)
panic+0x144/0x328
__stack_chk_fail+0x2c/0x30
pnv_smp_cpu_kill_self+0x2a0/0x2b0
cpu_die+0x48/0x70
arch_cpu_idle_dead+0x20/0x40
do_idle+0x274/0x390
cpu_startup_entry+0x38/0x50
start_secondary+0x5e4/0x600
start_secondary_prolog+0x10/0x14
Looking at the stack we see that the canary value in the stack frame
doesn't match the canary in the task/paca. That is because we have
reinitialised the task/paca value, but then the CPU coming online has
returned into a function using the old canary value. That causes the
comparison to fail.
Instead we can call boot_init_stack_canary() from start_secondary()
which never returns. This is essentially what the generic code does in
cpu_startup_entry() under #ifdef X86, we should make that non-x86
specific in a future patch.
Fixes: 7241d26e8175 ("powerpc/64: properly initialise the stackprotector canary on SMP.")
Reported-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
arch/powerpc/kernel/smp.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
From: Michael Ellerman <hidden> Date: 2018-10-22 10:16:46
On Fri, 2018-10-19 at 05:59:27 UTC, Michael Ellerman wrote:
Recently in commit 7241d26e8175 ("powerpc/64: properly initialise
the stackprotector canary on SMP.") we fixed a crash with stack
protector on SMP by initialising the stack canary in
cpu_idle_thread_init().
But this can also causes crashes, when a CPU comes back online after
being offline:
Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: pnv_smp_cpu_kill_self+0x2a0/0x2b0
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.19.0-rc3-gcc-7.3.1-00168-g4ffe713b7587 #94
Call Trace:
dump_stack+0xb0/0xf4 (unreliable)
panic+0x144/0x328
__stack_chk_fail+0x2c/0x30
pnv_smp_cpu_kill_self+0x2a0/0x2b0
cpu_die+0x48/0x70
arch_cpu_idle_dead+0x20/0x40
do_idle+0x274/0x390
cpu_startup_entry+0x38/0x50
start_secondary+0x5e4/0x600
start_secondary_prolog+0x10/0x14
Looking at the stack we see that the canary value in the stack frame
doesn't match the canary in the task/paca. That is because we have
reinitialised the task/paca value, but then the CPU coming online has
returned into a function using the old canary value. That causes the
comparison to fail.
Instead we can call boot_init_stack_canary() from start_secondary()
which never returns. This is essentially what the generic code does in
cpu_startup_entry() under #ifdef X86, we should make that non-x86
specific in a future patch.
Fixes: 7241d26e8175 ("powerpc/64: properly initialise the stackprotector canary on SMP.")
Reported-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Christophe Leroy <redacted>
From: Abdul Haleem <hidden> Date: 2018-10-22 13:44:20
On Fri, 2018-10-19 at 16:59 +1100, Michael Ellerman wrote:
quoted hunk
Recently in commit 7241d26e8175 ("powerpc/64: properly initialise
the stackprotector canary on SMP.") we fixed a crash with stack
protector on SMP by initialising the stack canary in
cpu_idle_thread_init().
But this can also causes crashes, when a CPU comes back online after
being offline:
Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: pnv_smp_cpu_kill_self+0x2a0/0x2b0
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.19.0-rc3-gcc-7.3.1-00168-g4ffe713b7587 #94
Call Trace:
dump_stack+0xb0/0xf4 (unreliable)
panic+0x144/0x328
__stack_chk_fail+0x2c/0x30
pnv_smp_cpu_kill_self+0x2a0/0x2b0
cpu_die+0x48/0x70
arch_cpu_idle_dead+0x20/0x40
do_idle+0x274/0x390
cpu_startup_entry+0x38/0x50
start_secondary+0x5e4/0x600
start_secondary_prolog+0x10/0x14
Looking at the stack we see that the canary value in the stack frame
doesn't match the canary in the task/paca. That is because we have
reinitialised the task/paca value, but then the CPU coming online has
returned into a function using the old canary value. That causes the
comparison to fail.
Instead we can call boot_init_stack_canary() from start_secondary()
which never returns. This is essentially what the generic code does in
cpu_startup_entry() under #ifdef X86, we should make that non-x86
specific in a future patch.
Fixes: 7241d26e8175 ("powerpc/64: properly initialise the stackprotector canary on SMP.")
Reported-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
arch/powerpc/kernel/smp.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
@@ -1316,6 +1310,8 @@ void start_secondary(void *unused)notify_cpu_starting(cpu);set_cpu_online(cpu,true);+boot_init_stack_canary();+local_irq_enable();/* We can enable ftrace for secondary cpus now */
Tested-by: Abdul Haleem <redacted>
--
Regard's
Abdul Haleem
IBM Linux Technology Centre