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| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2017-09-11 12:24:22 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-11-30 11:40:38 +0300 |
| commit | 27576413d9484cd9df933e3e4c802cb0cfb9c915 (patch) | |
| tree | 62e6adce80ae1d1dd148426a833433d06af11b93 | |
| parent | 21caac65d29b7d985a7cd1672ad1dd316b227974 (diff) | |
| download | linux-27576413d9484cd9df933e3e4c802cb0cfb9c915.tar.xz | |
s390/runtime instrumention: fix possible memory corruption
commit d6e646ad7cfa7034d280459b2b2546288f247144 upstream.
For PREEMPT enabled kernels the runtime instrumentation (RI) code
contains a possible use-after-free bug. If a task that makes use of RI
exits, it will execute do_exit() while still enabled for preemption.
That function will call exit_thread_runtime_instr() via
exit_thread(). If exit_thread_runtime_instr() gets preempted after the
RI control block of the task has been freed but before the pointer to
it is set to NULL, then save_ri_cb(), called from switch_to(), will
write to already freed memory.
Avoid this and simply disable preemption while freeing the control
block and setting the pointer to NULL.
Fixes: e4b8b3f33fca ("s390: add support for runtime instrumentation")
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/s390/kernel/runtime_instr.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/s390/kernel/runtime_instr.c b/arch/s390/kernel/runtime_instr.c index 32aefb215e59..d85c64821a6b 100644 --- a/arch/s390/kernel/runtime_instr.c +++ b/arch/s390/kernel/runtime_instr.c @@ -50,11 +50,13 @@ void exit_thread_runtime_instr(void) { struct task_struct *task = current; + preempt_disable(); if (!task->thread.ri_cb) return; disable_runtime_instr(); kfree(task->thread.ri_cb); task->thread.ri_cb = NULL; + preempt_enable(); } SYSCALL_DEFINE1(s390_runtime_instr, int, command) @@ -65,9 +67,7 @@ SYSCALL_DEFINE1(s390_runtime_instr, int, command) return -EOPNOTSUPP; if (command == S390_RUNTIME_INSTR_STOP) { - preempt_disable(); exit_thread_runtime_instr(); - preempt_enable(); return 0; } |