diff options
| author | Doug Berger <opendmb@gmail.com> | 2019-07-01 18:50:11 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-09-21 07:12:50 +0200 |
| commit | f1717aab217f818487835cd0cb6389266b0e19a4 (patch) | |
| tree | 15ee5e1c1a1f0320915ba911eaba26b4dba4af3b /arch/arm/mm | |
| parent | 77019b6089105abbb788d41a98f19492fcd89147 (diff) | |
ARM: 8874/1: mm: only adjust sections of valid mm structures
[ 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>
Diffstat (limited to 'arch/arm/mm')
| -rw-r--r-- | arch/arm/mm/init.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c index a9f6705aea23..731b7e64715b 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -691,7 +691,8 @@ 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); } read_unlock(&tasklist_lock); set_section_perms(perms, n, true, current->active_mm); |