Messages in this thread | | | Date | Tue, 3 Oct 2017 09:41:36 -0500 | From | Josh Poimboeuf <> | Subject | Re: [lockdep] b09be676e0 BUG: unable to handle kernel NULL pointer dereference at 000001f2 |
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On Tue, Oct 03, 2017 at 09:31:47AM -0500, Josh Poimboeuf wrote: > On Tue, Oct 03, 2017 at 10:06:34PM +0800, Fengguang Wu wrote: > > Hi Byungchul, > > > > This patch triggers a NULL-dereference bug at update_stack_state(). > > Although its parent commit also has a NULL-dereference bug, however > > the call stack looks rather different. Both dmesg files are attached. > > > > It also triggers this warning, which is being discussed in another > > thread, so CC Josh. The full dmesg attached, too. > > > > Please press Enter to activate this console. > > [ 138.605622] WARNING: kernel stack regs at be299c9a in procd:340 has bad 'bp' value 000001be > > [ 138.605627] unwind stack type:0 next_sp: (null) mask:0x2 graph_idx:0 > > [ 138.605631] be299c9a: 299ceb00 (0x299ceb00) > > [ 138.605633] be299c9e: 2281f1be (0x2281f1be) > > [ 138.605634] be299ca2: 299cebb6 (0x299cebb6) > > I suspect the bug is in: > > ce07a9415f26 ("locking/lockdep: Make check_prev_add() able to handle external stack_trace") > > It converts the stack-allocated stack_trace struct from static to > non-static, yet still adds it to a list. Does this fix it?
Actually, I spoke too soon. It's not actually adding the pointer to the list, it's copying its contents. So never mind...
-- Josh
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