From f9fa2908cfac967e15c94c8fe4d8cc36e4a0d842 Mon Sep 17 00:00:00 2001 From: "Bjoern A. Zeeb" Date: Wed, 9 Jun 2021 18:53:16 +0000 Subject: [PATCH] LinuxKPI: avoid userret: Returning with with pinned thread Some code manually calls local_bh_disable() and spin_lock() but then calls spin_unlock_bh() (or vice versa). Our code then calls local_bh_disable() again from spin_lock() which means we have the thread pin count increased twice and that means we get out of synch and are still pinned when returning to user space. Avoid this by adding the explicit local_bh_{enable,disable}() to the spin_[un]lock_bh() versions. Sponsored by: The FreeBSD Foundation Reviewed by: hselasky Differential Revision: https://reviews.freebsd.org/D30711 (cherry picked from commit 46ae23a4024b792c44a2b6c5f80429c40dac120b) --- sys/compat/linuxkpi/common/include/linux/spinlock.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/sys/compat/linuxkpi/common/include/linux/spinlock.h b/sys/compat/linuxkpi/common/include/linux/spinlock.h index 83f45b1a2a4..ca51fd23434 100644 --- a/sys/compat/linuxkpi/common/include/linux/spinlock.h +++ b/sys/compat/linuxkpi/common/include/linux/spinlock.h @@ -66,6 +66,7 @@ typedef struct { #define spin_lock_bh(_l) do { \ spin_lock(_l); \ + local_bh_disable(); \ } while (0) #define spin_lock_irq(_l) do { \ @@ -80,6 +81,7 @@ typedef struct { } while (0) #define spin_unlock_bh(_l) do { \ + local_bh_enable(); \ spin_unlock(_l); \ } while (0)