From mboxrd@z Thu Jan 1 00:00:00 1970 From: james.morse@arm.com (James Morse) Date: Fri, 23 Sep 2016 16:58:15 +0100 Subject: [PATCH] arm64: fix dump_backtrace with NULL tsk In-Reply-To: <1474642587-22416-1-git-send-email-mark.rutland@arm.com> References: <1474642587-22416-1-git-send-email-mark.rutland@arm.com> Message-ID: <57E55117.8080907@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Mark, On 23/09/16 15:56, Mark Rutland wrote: > In some places, dump_backtrace() is called with a NULL tsk parameter, > e.g. in bug_handler() in arch/arm64, or indirectly via show_stack() in > core code. The expectation is that this is treated as if current were > passed instead of NULL. > > Commit a80a0eb70c358f8c ("arm64: make irq_stack_ptr more robust") didn't > take this into account, and compares tsk against current *before* we > check if tsk is NULL. > > Due to this, we won't initialise irq_stack_ptr, and when we try to dump > the exception regs we may call dump_mem() for memory immediately above > the IRQ stack range, rather than for the relevant range on the task > stack. Bother, I should have spotted that. Thanks for catching this! Acked-by: James Morse Thanks, James