Re: BUG: unable to handle kernel NULL pointer dereference in sidtab_search_core
From: Eric Biggers <hidden>
Date: 2017-12-22 17:05:26
On Tue, Dec 19, 2017 at 11:48:02PM -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 SELinux: security_compute_sid: unrecognized SID 1 SELinux: security_compute_sid: unrecognized SID 1 SELinux: security_compute_sid: unrecognized SID 1 SELinux: security_compute_sid: unrecognized SID 1 SELinux: security_compute_sid: unrecognized SID 1 BUG: unable to handle kernel NULL pointer dereference at 0000000000000001 IP: sidtab_search_core+0x88/0x110 security/selinux/ss/sidtab.c:100 PGD 0 P4D 0 Oops: 0000 [#1] SMP Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 1 PID: 4252 Comm: kworker/u4:1 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:sidtab_search_core+0x88/0x110 security/selinux/ss/sidtab.c:100 RSP: 0018:ffffc900028abc18 EFLAGS: 00010293 RAX: ffff8802131a87c0 RBX: 0000000000000001 RCX: ffffffff8165d978 RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffff83fd17a0 RBP: ffffc900028abc40 R08: 0000000000000001 R09: 0000000000000001 R10: ffffc900028abbe0 R11: 0000000000000000 R12: 0000000000000001 R13: 0000000000000001 R14: 0000000000000000 R15: ffff880214d93800 FS: 0000000000000000(0000) GS:ffff88021fd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000001 CR3: 0000000214e31000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: sidtab_search+0x1f/0x30 security/selinux/ss/sidtab.c:111 security_compute_sid.part.11+0xe2/0x710 security/selinux/ss/services.c:1618 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: 8b 5b 50 48 85 db 75 e5 e8 e6 c9 c5 ff 49 8b 5f 18 48 85 db 75 10 eb 43 e8 d6 c9 c5 ff 48 8b 5b 50 48 85 db 74 35 e8 c8 c9 c5 ff <44> 8b 23 41 83 fc 02 76 e4 e8 ba c9 c5 ff 41 83 fc 03 75 1c 48 RIP: sidtab_search_core+0x88/0x110 security/selinux/ss/sidtab.c:100 RSP: ffffc900028abc18 CR2: 0000000000000001 ---[ end trace 571c0ea6c6959387 ]---
The reproducer for this is using AF_ALG and binding to the "pcrypt(gcm_base(ctr(aes-aesni),ghash-generic))" algorithm, so it's very likely 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) -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html