Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 07/70] kthread: fix boot hang (regression) on MIPS/OpenRISC | Date | Tue, 18 Sep 2018 00:41:40 +0200 |
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4.9-stable review patch. If anyone has any objections, please let me know.
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From: Vegard Nossum <vegard.nossum@oracle.com>
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: Amit Pundir <amit.pundir@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/mips/kernel/process.c | 1 - arch/openrisc/kernel/process.c | 2 -- 2 files changed, 3 deletions(-)
--- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -118,7 +118,6 @@ int copy_thread(unsigned long clone_flag 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; --- a/arch/openrisc/kernel/process.c +++ b/arch/openrisc/kernel/process.c @@ -152,8 +152,6 @@ copy_thread(unsigned long clone_flags, u 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);
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