diff options
authorPeter Zijlstra <peterz@infradead.org>2019-07-18 10:47:47 +0200
committerThomas Gleixner <tglx@linutronix.de>2019-07-18 16:47:24 +0200
commitcac9b9a4b08304f11daace03b8b48659355e44c1 (patch)
parent8e144797f1a67c52e386161863da4614a23ad913 (diff)
stacktrace: Force USER_DS for stack_trace_save_user()
When walking userspace stacks, USER_DS needs to be set, otherwise access_ok() will not function as expected. Reported-by: Vegard Nossum <vegard.nossum@oracle.com> Reported-by: Eiichi Tsukata <devel@etsukata.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Vegard Nossum <vegard.nossum@oracle.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Link: https://lkml.kernel.org/r/20190718085754.GM3402@hirez.programming.kicks-ass.net
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c
index e6a02b274b73..f5440abb7532 100644
--- a/kernel/stacktrace.c
+++ b/kernel/stacktrace.c
@@ -226,12 +226,17 @@ unsigned int stack_trace_save_user(unsigned long *store, unsigned int size)
.store = store,
.size = size,
+ mm_segment_t fs;
/* Trace user stack if not a kernel thread */
if (current->flags & PF_KTHREAD)
return 0;
+ fs = get_fs();
+ set_fs(USER_DS);
arch_stack_walk_user(consume_entry, &c, task_pt_regs(current));
+ set_fs(fs);
return c.len;

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