Commit cac9b9a4 authored Jul 18, 2019 by Peter Zijlstra Committed by Thomas Gleixner Jul 18, 2019

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

parent 8e144797

kernel/stacktrace.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -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

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