Messages in this thread | | | Date | Sat, 23 Dec 2017 14:38:26 -0600 | From | Eric Biggers <> | Subject | Re: BUG: unable to handle kernel NULL pointer dereference in irq_may_run |
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On Fri, Dec 22, 2017 at 08:13:47PM +0100, Thomas Gleixner wrote: > On Thu, 21 Dec 2017, syzbot wrote: > > > Hello, > > > > syzkaller hit the following crash on 6084b576dca2e898f5c101baef151f7bfdbb606d > > git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master > > compiler: gcc (GCC) 7.1.1 20170620 > > .config is attached > > Raw console output is attached. > > C reproducer is attached > > syzkaller reproducer is attached. See https://goo.gl/kgGztJ > > for information about syzkaller reproducers > > Unfortunately I cannot reproduce that issue. > > > BUG: unable to handle kernel NULL pointer dereference at (null) > > IP: irqd_has_set kernel/irq/internals.h:230 [inline] > > IP: irq_may_run+0x19/0x70 kernel/irq/chip.c:506 > > PGD 0 P4D 0 > > Oops: 0000 [#1] SMP > > Dumping ftrace buffer: > > (ftrace buffer empty) > > Modules linked in: > > CPU: 0 PID: 3177 Comm: kworker/u4:2 Not tainted 4.15.0-rc3-next-20171214+ #67 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google > > 01/01/2011 > > RIP: 0010:irqd_has_set kernel/irq/internals.h:230 [inline] > > So this dereferences > > irq_desc->irq_data->common > > which is NULL: > > 2b:* f7 00 00 00 0c 00 testl $0xc0000,(%rax) <-- trapping instruction > > > RIP: 0010:irq_may_run+0x19/0x70 kernel/irq/chip.c:506 > > RSP: 0018:ffff88021fc03f58 EFLAGS: 00010006 > > RAX: 0000000000000000 RBX: ffff8802151fa400 RCX: ffffffff81243385 > > ^^^^^^^^^^^^^^^^ > > > RDX: 0000000000010000 RSI: 0000000000000000 RDI: ffff8802151fa400 > > RBP: ffff88021fc03f68 R08: 0000000000000001 R09: 000000000000000c > > R10: ffff88021fc03ee8 R11: 000000000000000c R12: 0000000000000001 > > R13: ffff8802151fa400 R14: 0000000000000027 R15: 0000000000000000 > > FS: 0000000000000000(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 0000000000000000 CR3: 000000000301e003 CR4: 00000000001606f0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > Call Trace: > > <IRQ> > > handle_edge_irq+0x33/0x220 kernel/irq/chip.c:755 > > generic_handle_irq_desc include/linux/irqdesc.h:159 [inline] > > handle_irq+0x15/0x20 arch/x86/kernel/irq_64.c:77 > > do_IRQ+0x53/0x100 arch/x86/kernel/irq.c:229 > > common_interrupt+0xa9/0xa9 arch/x86/entry/entry_64.S:695 > > Now what confuses me is the fact that > > irq_desc->irq_data->common > > is initialized in desc_set_defaults() when the irq descriptor is > allocated. It's not written to after that. Plus it got dereferenced before. > So this looks like a stray pointer. > > I have no clue how that could be related to the reproducer. Is this > reproducing 100% on your end? If yes I surely can try to add some debug > which might help to catch this. > > Thanks, >
This is yet another one where the reproducer is using AF_ALG and binding to an algorithm using 'pcrypt', so it's running into the pcrypt_free() bug which is causing slab cache corruption:
https://groups.google.com/forum/#!topic/syzkaller-bugs/NKn_ivoPOpk
https://patchwork.kernel.org/patch/10126761/
So let's mark it as a duplicate:
#syz dup: KASAN: use-after-free Read in __list_del_entry_valid (2)
Eric
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