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| author |   Doug Berger <opendmb@gmail.com> | 2019-07-01 18:50:11 +0100 |
|---|---|---|
| committer |   Russell King <rmk+kernel@armlinux.org.uk> | 2019-08-23 11:32:36 +0100 |
| commit | c51bc12d06b3a5494fbfcbd788a8e307932a06e9 (patch) | |
| tree | 1be152722286130b0930674e5110f9492d088b6b /arch | |
| parent | Linux 5.3-rc5 (diff) | |
| download | linux-dev-c51bc12d06b3a5494fbfcbd788a8e307932a06e9.tar.xz linux-dev-c51bc12d06b3a5494fbfcbd788a8e307932a06e9.zip | |
ARM: 8874/1: mm: only adjust sections of valid mm structures
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>
Diffstat (limited to 'arch')
| -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 16d373d587c4..3a65ded832df 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -628,7 +628,8 @@ 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); |