backport: net: crypto set sk to NULL when af_alg_release

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
2019-02-21 14:39:03 +01:00 · 2019-02-21 14:39:03 +01:00 · cf6ea5cf34
commit cf6ea5cf34
parent c774433e2a
1 changed files with 118 additions and 0 deletions
--- a/patches/kernel/0011-net-crypto-set-sk-to-NULL-when-af_alg_release.patch
+++ b/patches/kernel/0011-net-crypto-set-sk-to-NULL-when-af_alg_release.patch
@ -0,0 +1,118 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Mao Wenan <maowenan@huawei.com>
+Date: Mon, 18 Feb 2019 10:44:44 +0800
+Subject: [PATCH] net: crypto set sk to NULL when af_alg_release.
+
+KASAN has found use-after-free in sockfs_setattr.
+The existed commit 6d8c50dcb029 ("socket: close race condition between sock_close()
+and sockfs_setattr()") is to fix this simillar issue, but it seems to ignore
+that crypto module forgets to set the sk to NULL after af_alg_release.
+
+KASAN report details as below:
+BUG: KASAN: use-after-free in sockfs_setattr+0x120/0x150
+Write of size 4 at addr ffff88837b956128 by task syz-executor0/4186
+
+CPU: 2 PID: 4186 Comm: syz-executor0 Not tainted xxx + #1
+Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
+1.10.2-1ubuntu1 04/01/2014
+Call Trace:
+ dump_stack+0xca/0x13e
+ print_address_description+0x79/0x330
+ ? vprintk_func+0x5e/0xf0
+ kasan_report+0x18a/0x2e0
+ ? sockfs_setattr+0x120/0x150
+ sockfs_setattr+0x120/0x150
+ ? sock_register+0x2d0/0x2d0
+ notify_change+0x90c/0xd40
+ ? chown_common+0x2ef/0x510
+ chown_common+0x2ef/0x510
+ ? chmod_common+0x3b0/0x3b0
+ ? __lock_is_held+0xbc/0x160
+ ? __sb_start_write+0x13d/0x2b0
+ ? __mnt_want_write+0x19a/0x250
+ do_fchownat+0x15c/0x190
+ ? __ia32_sys_chmod+0x80/0x80
+ ? trace_hardirqs_on_thunk+0x1a/0x1c
+ __x64_sys_fchownat+0xbf/0x160
+ ? lockdep_hardirqs_on+0x39a/0x5e0
+ do_syscall_64+0xc8/0x580
+ entry_SYSCALL_64_after_hwframe+0x49/0xbe
+RIP: 0033:0x462589
+Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 48 89 f8 48 89
+f7 48 89 d6 48 89
+ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3
+48 c7 c1 bc ff ff
+ff f7 d8 64 89 01 48
+RSP: 002b:00007fb4b2c83c58 EFLAGS: 00000246 ORIG_RAX: 0000000000000104
+RAX: ffffffffffffffda RBX: 000000000072bfa0 RCX: 0000000000462589
+RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000000000007
+RBP: 0000000000000005 R08: 0000000000001000 R09: 0000000000000000
+R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb4b2c846bc
+R13: 00000000004bc733 R14: 00000000006f5138 R15: 00000000ffffffff
+
+Allocated by task 4185:
+ kasan_kmalloc+0xa0/0xd0
+ __kmalloc+0x14a/0x350
+ sk_prot_alloc+0xf6/0x290
+ sk_alloc+0x3d/0xc00
+ af_alg_accept+0x9e/0x670
+ hash_accept+0x4a3/0x650
+ __sys_accept4+0x306/0x5c0
+ __x64_sys_accept4+0x98/0x100
+ do_syscall_64+0xc8/0x580
+ entry_SYSCALL_64_after_hwframe+0x49/0xbe
+
+Freed by task 4184:
+ __kasan_slab_free+0x12e/0x180
+ kfree+0xeb/0x2f0
+ __sk_destruct+0x4e6/0x6a0
+ sk_destruct+0x48/0x70
+ __sk_free+0xa9/0x270
+ sk_free+0x2a/0x30
+ af_alg_release+0x5c/0x70
+ __sock_release+0xd3/0x280
+ sock_close+0x1a/0x20
+ __fput+0x27f/0x7f0
+ task_work_run+0x136/0x1b0
+ exit_to_usermode_loop+0x1a7/0x1d0
+ do_syscall_64+0x461/0x580
+ entry_SYSCALL_64_after_hwframe+0x49/0xbe
+
+Syzkaller reproducer:
+r0 = perf_event_open(&(0x7f0000000000)={0x0, 0x70, 0x0, 0x0, 0x0, 0x0,
+0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, @perf_config_ext}, 0x0, 0x0,
+0xffffffffffffffff, 0x0)
+r1 = socket$alg(0x26, 0x5, 0x0)
+getrusage(0x0, 0x0)
+bind(r1, &(0x7f00000001c0)=@alg={0x26, 'hash\x00', 0x0, 0x0,
+'sha256-ssse3\x00'}, 0x80)
+r2 = accept(r1, 0x0, 0x0)
+r3 = accept4$unix(r2, 0x0, 0x0, 0x0)
+r4 = dup3(r3, r0, 0x0)
+fchownat(r4, &(0x7f00000000c0)='\x00', 0x0, 0x0, 0x1000)
+
+Fixes: 6d8c50dcb029 ("socket: close race condition between sock_close() and sockfs_setattr()")
+Signed-off-by: Mao Wenan <maowenan@huawei.com>
+Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
+---
+ crypto/af_alg.c | 4 +++-
+ 1 file changed, 3 insertions(+), 1 deletion(-)
+
+diff --git a/crypto/af_alg.c b/crypto/af_alg.c
+index 671e42ff21d4..493002afae73 100644
+--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
+@@ -122,8 +122,10 @@ static void alg_do_release(const struct af_alg_type *type, void *private)
+ 
+ int af_alg_release(struct socket *sock)
+ {
+-	if (sock->sk)
+	if (sock->sk) {
+ 		sock_put(sock->sk);
+		sock->sk = NULL;
+	}
+ 	return 0;
+ }
+ EXPORT_SYMBOL_GPL(af_alg_release);