Re: GPF in lrw_crypt
From: Dmitry Vyukov <dvyukov@google.com>
Date: 2015-12-24 11:04:14
Also in:
lkml
On Thu, Dec 24, 2015 at 10:39 AM, Herbert Xu [off-list ref] wrote:
quoted hunk ↗ jump to hunk
On Thu, Dec 17, 2015 at 01:59:11PM +0100, Dmitry Vyukov wrote:quoted
The following program causes GPF in lrw_crypt:OK, this is a result of certain implementations (such as lrw) not coping with there being no key gracefully. I think the easiest way is probably to check this in algif_skcipher. ---8<--- Subject: crypto: algif_skcipher - Require setkey before accept(2) Some cipher implementations will crash if you try to use them without calling setkey first. This patch adds a check so that the accept(2) call will fail with -ENOKEY if setkey hasn't been done on the socket yet. Cc: stable@vger.kernel.org Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c index 5c756b3..b62c973 100644 --- a/crypto/algif_skcipher.c +++ b/crypto/algif_skcipher.c@@ -31,6 +31,11 @@ struct skcipher_sg_list { struct scatterlist sg[0]; }; +struct skcipher_tfm { + struct crypto_skcipher *skcipher; + bool has_key; +}; + struct skcipher_ctx { struct list_head tsgl; struct af_alg_sgl rsgl;@@ -750,17 +755,38 @@ static struct proto_ops algif_skcipher_ops = { static void *skcipher_bind(const char *name, u32 type, u32 mask) { - return crypto_alloc_skcipher(name, type, mask); + struct skcipher_tfm *tfm; + + tfm = kzalloc(sizeof(*tfm), GFP_KERNEL); + if (!tfm) + return ERR_PTR(-ENOMEM); + + tfm->skcipher = crypto_alloc_skcipher(name, type, mask); + if (IS_ERR(tfm->skcipher)) { + kfree(tfm); + return ERR_CAST(tfm->skcipher); + } + + return tfm; } static void skcipher_release(void *private) { - crypto_free_skcipher(private); + struct skcipher_tfm *tfm = private; + + crypto_free_skcipher(tfm->skcipher); + kfree(tfm); } static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen) { - return crypto_skcipher_setkey(private, key, keylen); + struct skcipher_tfm *tfm = private; + int err; + + err = crypto_skcipher_setkey(tfm->skcipher, key, keylen); + tfm->has_key = !err; + + return err; } static void skcipher_wait(struct sock *sk)@@ -792,20 +818,25 @@ static int skcipher_accept_parent(void *private, struct sock *sk) { struct skcipher_ctx *ctx; struct alg_sock *ask = alg_sk(sk); - unsigned int len = sizeof(*ctx) + crypto_skcipher_reqsize(private); + struct skcipher_tfm *tfm = private; + struct crypto_skcipher *skcipher = tfm->skcipher; + unsigned int len = sizeof(*ctx) + crypto_skcipher_reqsize(skcipher); + + if (!tfm->has_key) + return -ENOKEY; ctx = sock_kmalloc(sk, len, GFP_KERNEL); if (!ctx) return -ENOMEM; - ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(private), + ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(skcipher), GFP_KERNEL); if (!ctx->iv) { sock_kfree_s(sk, ctx, len); return -ENOMEM; } - memset(ctx->iv, 0, crypto_skcipher_ivsize(private)); + memset(ctx->iv, 0, crypto_skcipher_ivsize(skcipher)); INIT_LIST_HEAD(&ctx->tsgl); ctx->len = len;@@ -818,7 +849,7 @@ static int skcipher_accept_parent(void *private, struct sock *sk) ask->private = ctx; - skcipher_request_set_tfm(&ctx->req, private); + skcipher_request_set_tfm(&ctx->req, skcipher); skcipher_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG, af_alg_complete, &ctx->completion);
Hi Herbert, I am testing with your two patches: crypto: algif_skcipher - Use new skcipher interface crypto: algif_skcipher - Require setkey before accept(2) on top of a88164345b81292b55a8d4829fdd35c8d611cd7d (Dec 23). Now the following program causes a bunch of use-after-frees and them kills kernel: // autogenerated by syzkaller (http://github.com/google/syzkaller) #include <unistd.h> #include <sys/syscall.h> #include <string.h> #include <stdint.h> #include <pthread.h> long r[10]; int main() { memset(r, -1, sizeof(r)); r[0] = syscall(SYS_mmap, 0x20000000ul, 0xca7000ul, 0x3ul, 0x32ul, 0xfffffffffffffffful, 0x0ul); memcpy((void*)0x20ca6bc1, "\x2e\x2f\x63\x6f\x6e\x74\x72\x6f\x6c\x00", 10); r[2] = syscall(SYS_creat, 0x20ca6bc1ul, 0x28ul, 0, 0, 0, 0); r[3] = syscall(SYS_socket, 0x26ul, 0x5ul, 0x0ul, 0, 0, 0); *(uint16_t*)0x20000986 = (uint16_t)0x26; memcpy((void*)0x20000988, "\x73\x6b\x63\x69\x70\x68\x65\x72\x00\x00\x00\x00\x00\x00", 14); *(uint32_t*)0x20000996 = (uint32_t)0x1; *(uint32_t*)0x2000099a = (uint32_t)0xf; memcpy((void*)0x2000099e, "\x5f\x5f\x65\x63\x62\x2d\x73\x65\x72\x70\x65\x6e\x74\x2d\x73\x73\x65\x32\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", 64); r[9] = syscall(SYS_bind, r[3], 0x20000986ul, 0x58ul, 0, 0, 0); return 0; } ================================================================== BUG: KASAN: use-after-free in skcipher_bind+0xe1/0x100 at addr ffff88003398bab0 Read of size 8 by task syz-executor/15123 ============================================================================= BUG kmalloc-16 (Not tainted): kasan: bad access detected ----------------------------------------------------------------------------- Disabling lock debugging due to kernel taint INFO: Allocated in skcipher_bind+0x55/0x100 age=36 cpu=1 pid=15123 [< none >] ___slab_alloc+0x489/0x4e0 mm/slub.c:2468 [< none >] __slab_alloc+0x4c/0x90 mm/slub.c:2497 [< inline >] slab_alloc_node mm/slub.c:2560 [< inline >] slab_alloc mm/slub.c:2602 [< none >] kmem_cache_alloc_trace+0x264/0x2f0 mm/slub.c:2619 [< inline >] kmalloc include/linux/slab.h:458 [< inline >] kzalloc include/linux/slab.h:602 [< none >] skcipher_bind+0x55/0x100 crypto/algif_skcipher.c:760 [< none >] alg_bind+0x18e/0x3a0 crypto/af_alg.c:155 [< none >] SYSC_bind+0x1ea/0x250 net/socket.c:1376 [< none >] SyS_bind+0x24/0x30 net/socket.c:1362 [< none >] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 INFO: Freed in skcipher_bind+0xbd/0x100 age=7 cpu=2 pid=15123 [< none >] __slab_free+0x1fc/0x320 mm/slub.c:2678 [< inline >] slab_free mm/slub.c:2833 [< none >] kfree+0x26a/0x290 mm/slub.c:3662 [< none >] skcipher_bind+0xbd/0x100 crypto/algif_skcipher.c:766 [< none >] alg_bind+0x18e/0x3a0 crypto/af_alg.c:155 [< none >] SYSC_bind+0x1ea/0x250 net/socket.c:1376 [< none >] SyS_bind+0x24/0x30 net/socket.c:1362 [< none >] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 Call Trace: [< inline >] __dump_stack lib/dump_stack.c:15 [<ffffffff8289a21d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50 [<ffffffff816c56f4>] print_trailer+0xf4/0x150 mm/slub.c:659 [<ffffffff816cbeaf>] object_err+0x2f/0x40 mm/slub.c:689 [< inline >] print_address_description mm/kasan/report.c:138 [<ffffffff816ce86d>] kasan_report_error+0x25d/0x560 mm/kasan/report.c:251 [< inline >] kasan_report mm/kasan/report.c:274 [<ffffffff816cec6e>] __asan_report_load8_noabort+0x3e/0x40 mm/kasan/report.c:295 [<ffffffff827ddb41>] skcipher_bind+0xe1/0x100 crypto/algif_skcipher.c:767 [<ffffffff827da38e>] alg_bind+0x18e/0x3a0 crypto/af_alg.c:155 [<ffffffff84b5a0ba>] SYSC_bind+0x1ea/0x250 net/socket.c:1376 [<ffffffff84b5c7e4>] SyS_bind+0x24/0x30 net/socket.c:1362 [<ffffffff85c8b376>] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 ================================================================== ================================================================== BUG: KASAN: use-after-free in skcipher_release+0x43/0x50 at addr ffff88003398b4f8 Read of size 8 by task syz-executor/15123 ============================================================================= BUG kmalloc-16 (Tainted: G B ): kasan: bad access detected ----------------------------------------------------------------------------- INFO: Allocated in kstrdup_const+0x46/0x60 age=28033 cpu=0 pid=14775 [< none >] ___slab_alloc+0x489/0x4e0 mm/slub.c:2468 [< none >] __slab_alloc+0x4c/0x90 mm/slub.c:2497 [< inline >] slab_alloc mm/slub.c:2560 [< none >] __kmalloc_track_caller+0x278/0x310 mm/slub.c:4066 [< none >] kstrdup+0x39/0x70 mm/util.c:53 [< none >] kstrdup_const+0x46/0x60 mm/util.c:74 [< none >] alloc_vfsmnt+0xe7/0x760 fs/namespace.c:212 [< none >] clone_mnt+0x74/0xa20 fs/namespace.c:973 [< none >] copy_tree+0x3c0/0x940 fs/namespace.c:1713 [< none >] copy_mnt_ns+0x110/0x8b0 fs/namespace.c:2800 [< none >] create_new_namespaces+0xd0/0x610 kernel/nsproxy.c:70 [< none >] unshare_nsproxy_namespaces+0xa9/0x1d0 kernel/nsproxy.c:190 [< inline >] SYSC_unshare kernel/fork.c:2008 [< none >] SyS_unshare+0x3b0/0x800 kernel/fork.c:1958 [< none >] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 INFO: Freed in kfree_const+0x39/0x50 age=28020 cpu=1 pid=7161 [< none >] __slab_free+0x1fc/0x320 mm/slub.c:2678 [< inline >] slab_free mm/slub.c:2833 [< none >] kfree+0x26a/0x290 mm/slub.c:3662 [< none >] kfree_const+0x39/0x50 mm/util.c:35 [< none >] free_vfsmnt+0x37/0x80 fs/namespace.c:580 [< none >] delayed_free_vfsmnt+0x16/0x20 fs/namespace.c:589 [< inline >] __rcu_reclaim kernel/rcu/rcu.h:118 [< inline >] rcu_do_batch kernel/rcu/tree.c:2694 [< inline >] invoke_rcu_callbacks kernel/rcu/tree.c:2962 [< inline >] __rcu_process_callbacks kernel/rcu/tree.c:2929 [< none >] rcu_process_callbacks+0xc71/0x1380 kernel/rcu/tree.c:2946 [< none >] __do_softirq+0x23b/0x8a0 kernel/softirq.c:273 [< inline >] invoke_softirq kernel/softirq.c:350 [< none >] irq_exit+0x15d/0x190 kernel/softirq.c:391 [< inline >] exiting_irq ./arch/x86/include/asm/apic.h:653 [< none >] smp_apic_timer_interrupt+0x83/0xa0 arch/x86/kernel/apic/apic.c:926 [< none >] apic_timer_interrupt+0x8c/0xa0 arch/x86/entry/entry_64.S:520 [< none >] percpu_down_read_trylock+0x22/0xc0 kernel/locking/percpu-rwsem.c:87 [< none >] __sb_start_write+0x116/0x130 fs/super.c:1200 [< inline >] sb_start_write_trylock include/linux/fs.h:1454 [< none >] touch_atime+0x130/0x280 fs/inode.c:1643 [< inline >] file_accessed include/linux/fs.h:1916 [< none >] pipe_read+0x70d/0xb20 fs/pipe.c:328 [< inline >] new_sync_read fs/read_write.c:422 [< none >] __vfs_read+0x2fd/0x460 fs/read_write.c:434 [< none >] vfs_read+0x106/0x310 fs/read_write.c:454 Call Trace: [< inline >] __dump_stack lib/dump_stack.c:15 [<ffffffff8289a21d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50 [<ffffffff816c56f4>] print_trailer+0xf4/0x150 mm/slub.c:659 [<ffffffff816cbeaf>] object_err+0x2f/0x40 mm/slub.c:689 [< inline >] print_address_description mm/kasan/report.c:138 [<ffffffff816ce86d>] kasan_report_error+0x25d/0x560 mm/kasan/report.c:251 [< inline >] kasan_report mm/kasan/report.c:274 [<ffffffff816cec6e>] __asan_report_load8_noabort+0x3e/0x40 mm/kasan/report.c:295 [<ffffffff827dda53>] skcipher_release+0x43/0x50 crypto/algif_skcipher.c:777 [< inline >] alg_do_release crypto/af_alg.c:116 [<ffffffff827d9d8c>] alg_sock_destruct+0x8c/0xe0 crypto/af_alg.c:315 [<ffffffff84b6bb0a>] sk_destruct+0x4a/0x490 net/core/sock.c:1447 [<ffffffff84b6bfa7>] __sk_free+0x57/0x200 net/core/sock.c:1475 [<ffffffff84b6c180>] sk_free+0x30/0x40 net/core/sock.c:1486 [< inline >] sock_put include/net/sock.h:1627 [<ffffffff827d95db>] af_alg_release+0x5b/0x70 crypto/af_alg.c:123 [<ffffffff84b55aed>] sock_release+0x8d/0x1d0 net/socket.c:571 [<ffffffff84b55c46>] sock_close+0x16/0x20 net/socket.c:1022 [<ffffffff81716103>] __fput+0x233/0x780 fs/file_table.c:208 [<ffffffff817166d5>] ____fput+0x15/0x20 fs/file_table.c:244 [<ffffffff8134679b>] task_work_run+0x16b/0x200 kernel/task_work.c:115 [< inline >] exit_task_work include/linux/task_work.h:21 [<ffffffff812f4d3b>] do_exit+0x8bb/0x2b20 kernel/exit.c:750 [<ffffffff812f7118>] do_group_exit+0x108/0x320 kernel/exit.c:880 [< inline >] SYSC_exit_group kernel/exit.c:891 [<ffffffff812f734d>] SyS_exit_group+0x1d/0x20 kernel/exit.c:889 [<ffffffff85c8b376>] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 ================================================================== ... a bunch of reports skipped ... BUG: unable to handle kernel NULL pointer dereference at 0000000000000028 Fixing recursive fault but reboot is needed!