| From | Sasha Levin <> | Subject | [PATCH AUTOSEL 5.2 72/85] stacktrace: Force USER_DS for stack_trace_save_user() | Date | Fri, 26 Jul 2019 09:39:22 -0400 |
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From: Peter Zijlstra <peterz@infradead.org>
[ Upstream commit cac9b9a4b08304f11daace03b8b48659355e44c1 ]
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 Signed-off-by: Sasha Levin <sashal@kernel.org> --- kernel/stacktrace.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c index 36139de0a3c4..899b726c9e98 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->mm) 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 -- 2.20.1
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