Hugh Dickins b81ff1013e x86/fpu: Use fault_in_pages_writeable() for pre-faulting ... Since commit d9c9ce34ed ("x86/fpu: Fault-in user stack if copy_fpstate_to_sigframe() fails") get_user_pages_unlocked() pre-faults user's memory if a write generates a page fault while the handler is disabled. This works in general and uncovered a bug as reported by Mike Rapoport¹. It has been pointed out that this function may be fragile and a simple pre-fault as in fault_in_pages_writeable() would be a better solution. Better as in taste and simplicity: that write (as performed by the alternative function) performs exactly the same faulting of memory as before. This was suggested by Hugh Dickins and Andrew Morton. Use fault_in_pages_writeable() for pre-faulting user's stack. [ bigeasy: Write commit message. ] [ bp: Massage some. ] ¹ https://lkml.kernel.org/r/1557844195-18882-1-git-send-email-rppt@linux.ibm.com Fixes: d9c9ce34ed ("x86/fpu: Fault-in user stack if copy_fpstate_to_sigframe() fails") Suggested-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Tested-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: linux-mm <linux-mm@kvack.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/20190529072540.g46j4kfeae37a3iu@linutronix.de Link: https://lkml.kernel.org/r/1557844195-18882-1-git-send-email-rppt@linux.ibm.com		2019-06-06 19:15:17 +02:00
..
bugs.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
core.c	treewide: Add SPDX license identifier for missed files	2019-05-21 10:50:45 +02:00
init.c	treewide: Add SPDX license identifier for missed files	2019-05-21 10:50:45 +02:00
Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
regset.c	x86/fpu: Remove fpu->initialized	2019-04-10 15:42:40 +02:00
signal.c	x86/fpu: Use fault_in_pages_writeable() for pre-faulting	2019-06-06 19:15:17 +02:00
xstate.c	treewide: Add SPDX license identifier for missed files	2019-05-21 10:50:45 +02:00