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| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2021-08-19 22:30:30 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2021-08-20 13:15:54 +0300 |
| commit | b857174e68e26f9c4f0796971e11eb63ad5a3eb6 (patch) | |
| tree | 009dd241c14645e5ec8bc14d2ef6e8fa23b80dbb | |
| parent | 9ae6ab27f44ee0da47520011afc04218f90e8b12 (diff) | |
| download | linux-b857174e68e26f9c4f0796971e11eb63ad5a3eb6.tar.xz | |
locking/ww_mutex: Initialize waiter.ww_ctx properly
The consolidation of the debug code for mutex waiter intialization sets
waiter::ww_ctx to a poison value unconditionally. For regular mutexes this
is intended to catch the case where waiter_ww_ctx is dereferenced
accidentally.
For ww_mutex the poison value has to be overwritten either with a context
pointer or NULL for ww_mutexes without context.
The rework broke this as it made the store conditional on the context
pointer instead of the argument which signals whether ww_mutex code should
be compiled in or optiized out. As a result waiter::ww_ctx ends up with the
poison pointer for contextless ww_mutexes which causes a later dereference of
the poison pointer because it is != NULL.
Use the build argument instead so for ww_mutex the poison value is always
overwritten.
Fixes: c0afb0ffc06e6 ("locking/ww_mutex: Gather mutex_waiter initialization")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210819193030.zpwrpvvrmy7xxxiy@linutronix.de
| -rw-r--r-- | kernel/locking/mutex.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index 3a65bf4bacfd..d456579d0952 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -618,7 +618,7 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas debug_mutex_lock_common(lock, &waiter); waiter.task = current; - if (ww_ctx) + if (use_ww_ctx) waiter.ww_ctx = ww_ctx; lock_contended(&lock->dep_map, ip); |