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stacktrace: Force USER_DS for stack_trace_save_user()

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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
This commit is contained in:
Peter Zijlstra
2019-07-18 10:47:47 +02:00
committed by Thomas Gleixner
parent 8e144797f1
commit cac9b9a4b0
1 changed files with 5 additions and 0 deletions
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5
kernel/stacktrace.c
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@@ -226,12 +226,17 @@ unsigned int stack_trace_save_user(unsigned long *store, unsigned int size)
.store = store, .store = store,
.size = size, .size = size,
}; };
mm_segment_t fs;
/* Trace user stack if not a kernel thread */ /* Trace user stack if not a kernel thread */
if (current->flags & PF_KTHREAD) if (current->flags & PF_KTHREAD)
return 0; return 0;
fs = get_fs();
set_fs(USER_DS);
arch_stack_walk_user(consume_entry, &c, task_pt_regs(current)); arch_stack_walk_user(consume_entry, &c, task_pt_regs(current));
set_fs(fs);
return c.len; return c.len;
} }
#endif #endif