Messages in this thread Patch in this message | | | Date | Tue, 3 Oct 2017 09:31:47 -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 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?
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 44c8d0d17170..b4a5e60488aa 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -1986,7 +1986,7 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next) { int depth = curr->lockdep_depth; struct held_lock *hlock; - struct stack_trace trace; + static struct stack_trace trace; int (*save)(struct stack_trace *trace) = save_trace; /*
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