On Fri, Dec 22, 2017 at 01:38:01PM -0800, 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 > > > BUG: unable to handle kernel paging request at 00000000830e2118 > IP: security_compute_sid.part.11+0x418/0x710 > security/selinux/ss/services.c:1640 > PGD 0 P4D 0 > Oops: 0000 [#1] SMP > Dumping ftrace buffer: > (ftrace buffer empty) > Modules linked in: > CPU: 0 PID: 3391 Comm: kworker/u4:0 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:security_compute_sid.part.11+0x418/0x710 > security/selinux/ss/services.c:1640 > RSP: 0018:ffffc90001993c70 EFLAGS: 00010293 > RAX: ffff880216ba0800 RBX: 0000000000000002 RCX: ffffffff81667b88 > RDX: 0000000000000000 RSI: 0000000000000005 RDI: ffffffff83fd17a0 > RBP: ffffc90001993d20 R08: 0000000000000001 R09: 0000000000000001 > R10: ffffc90001993be0 R11: 0000000000000000 R12: ffff88021694f188 > R13: 0000000000000010 R14: ffff880216592388 R15: 00000000830e20e0 > FS: 0000000000000000(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00000000830e2118 CR3: 000000000301e001 CR4: 00000000001606f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > security_compute_sid+0x92/0xa0 security/selinux/ss/services.c:1598 > security_transition_sid+0x57/0x70 security/selinux/ss/services.c:1764 > selinux_bprm_set_creds+0x215/0x2f0 security/selinux/hooks.c:2423 > security_bprm_set_creds+0x41/0x60 security/security.c:332 > prepare_binprm+0xae/0x1f0 fs/exec.c:1561 > do_execveat_common.isra.30+0x6f7/0xb90 fs/exec.c:1784 > do_execve+0x31/0x40 fs/exec.c:1848 > call_usermodehelper_exec_async+0x104/0x190 kernel/umh.c:100 > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:524 > Code: 40 74 15 41 83 fd 10 74 0f e8 d5 27 c5 ff 4d 85 ff 75 33 e9 6f 02 00 > 00 e8 c6 27 c5 ff 4d 85 ff 0f 84 e6 02 00 00 e8 b8 27 c5 ff <41> 80 7f 38 02 > 0f 84 5c 01 00 00 e8 a8 27 c5 ff 41 8b 06 89 45 > RIP: security_compute_sid.part.11+0x418/0x710 > security/selinux/ss/services.c:1640 RSP: ffffc90001993c70 > CR2: 00000000830e2118 > ---[ end trace fe59d8175af57ffc ]--- > Kernel panic - not syncing: Fatal exception > Dumping ftrace buffer: > (ftrace buffer empty) > Kernel Offset: disabled > Rebooting in 86400 seconds.. > This is yet another one where the reproducer is using AF_ALG and binding to the "pcrypt(gcm_base(ctr(aes-aesni),ghash-generic))" algorithm, 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) I wonder if it would be of any help to disable slab cache merging, i.e. set CONFIG_SLAB_MERGE_DEFAULT=n? That would reduce the number of duplicate reports, though perhaps at the risk of hiding bugs. Eric
