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authorVegard Nossum <vegard.nossum@oracle.com>2017-05-29 09:22:07 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-06-14 15:07:51 +0200
commit2c2c50379270a92205ba2f4a1786b248299797c8 (patch)
parent1a422e547a65c949a52074f830259f57ed665824 (diff)
kthread: fix boot hang (regression) on MIPS/OpenRISC
commit b0f5a8f32e8bbdaae1abb8abe2d3cbafaba57e08 upstream. This fixes a regression in commit 4d6501dce079 where I didn't notice that MIPS and OpenRISC were reinitialising p->{set,clear}_child_tid to NULL after our initialisation in copy_process(). We can simply get rid of the arch-specific initialisation here since it is now always done in copy_process() before hitting copy_thread{,_tls}(). Review notes: - As far as I can tell, copy_process() is the only user of copy_thread_tls(), which is the only caller of copy_thread() for architectures that don't implement copy_thread_tls(). - After this patch, there is no arch-specific code touching p->set_child_tid or p->clear_child_tid whatsoever. - It may look like MIPS/OpenRISC wanted to always have these fields be NULL, but that's not true, as copy_process() would unconditionally set them again _after_ calling copy_thread_tls() before commit 4d6501dce079. Fixes: 4d6501dce079c1eb6bf0b1d8f528a5e81770109e ("kthread: Fix use-after-free if kthread fork fails") Reported-by: Guenter Roeck <linux@roeck-us.net> Tested-by: Guenter Roeck <linux@roeck-us.net> # MIPS only Acked-by: Stafford Horne <shorne@gmail.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org Cc: Jonas Bonn <jonas@southpole.se> Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> Cc: openrisc@lists.librecores.org Cc: Jamie Iles <jamie.iles@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2 files changed, 0 insertions, 3 deletions
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index b68e10fc453d..0f88015f3bfa 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -120,7 +120,6 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
struct thread_info *ti = task_thread_info(p);
struct pt_regs *childregs, *regs = current_pt_regs();
unsigned long childksp;
- p->set_child_tid = p->clear_child_tid = NULL;
childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
diff --git a/arch/openrisc/kernel/process.c b/arch/openrisc/kernel/process.c
index f8da545854f9..106859ae27ff 100644
--- a/arch/openrisc/kernel/process.c
+++ b/arch/openrisc/kernel/process.c
@@ -167,8 +167,6 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
top_of_kernel_stack = sp;
- p->set_child_tid = p->clear_child_tid = NULL;
/* Locate userspace context on stack... */
sp -= STACK_FRAME_OVERHEAD; /* redzone */
sp -= sizeof(struct pt_regs);