From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 18 Jul 2019 10:47:47 +0200
Subject: stacktrace: Force USER_DS for stack_trace_save_user()
Git-commit: cac9b9a4b08304f11daace03b8b48659355e44c1
Patch-mainline: v5.3-rc1
References: jsc#SLE-11178
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
Acked-by: Miroslav Benes <mbenes@suse.cz>
---
kernel/stacktrace.c | 5 +++++
1 file changed, 5 insertions(+)
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;
}
#endif