From cf6ea5cf3482781a5e93bb88f526c821bba7ca0d Mon Sep 17 00:00:00 2001 From: Thomas Lamprecht Date: Thu, 21 Feb 2019 14:39:03 +0100 Subject: [PATCH] backport: net: crypto set sk to NULL when af_alg_release Signed-off-by: Thomas Lamprecht --- ...o-set-sk-to-NULL-when-af_alg_release.patch | 118 ++++++++++++++++++ 1 file changed, 118 insertions(+) create mode 100644 patches/kernel/0011-net-crypto-set-sk-to-NULL-when-af_alg_release.patch diff --git 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 new file mode 100644 index 0000000..8450fd2 --- /dev/null +++ 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 +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 +Signed-off-by: Thomas Lamprecht +--- + 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); -- 2.39.2