Messages in this thread Patch in this message | | | From | Sasha Levin <> | Subject | [PATCH AUTOSEL 4.14 14/36] ARM: 8874/1: mm: only adjust sections of valid mm structures | Date | Wed, 4 Sep 2019 12:01:00 -0400 |
| |
From: Doug Berger <opendmb@gmail.com>
[ Upstream commit c51bc12d06b3a5494fbfcbd788a8e307932a06e9 ]
A timing hazard exists when an early fork/exec thread begins exiting and sets its mm pointer to NULL while a separate core tries to update the section information.
This commit ensures that the mm pointer is not NULL before setting its section parameters. The arguments provided by commit 11ce4b33aedc ("ARM: 8672/1: mm: remove tasklist locking from update_sections_early()") are equally valid for not requiring grabbing the task_lock around this check.
Fixes: 08925c2f124f ("ARM: 8464/1: Update all mm structures with section adjustments") Signed-off-by: Doug Berger <opendmb@gmail.com> Acked-by: Laura Abbott <labbott@redhat.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Florian Fainelli <f.fainelli@gmail.com> Cc: Rob Herring <robh@kernel.org> Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org> Cc: Peng Fan <peng.fan@nxp.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> Signed-off-by: Sasha Levin <sashal@kernel.org> --- arch/arm/mm/init.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c index defb7fc264280..4fa12fcf1f5d8 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -722,7 +722,8 @@ static void update_sections_early(struct section_perm perms[], int n) if (t->flags & PF_KTHREAD) continue; for_each_thread(t, s) - set_section_perms(perms, n, true, s->mm); + if (s->mm) + set_section_perms(perms, n, true, s->mm); } set_section_perms(perms, n, true, current->active_mm); set_section_perms(perms, n, true, &init_mm); -- 2.20.1
| |