From: Enzo Matsumiya ematsumiya@suse.de
commit b0abcd65ec545701b8793e12bc27dc98042b151a upstream.
Doing an async decryption (large read) crashes with a slab-use-after-free way down in the crypto API.
Reproducer: # mount.cifs -o ...,seal,esize=1 //srv/share /mnt # dd if=/mnt/largefile of=/dev/null ... [ 194.196391] ================================================================== [ 194.196844] BUG: KASAN: slab-use-after-free in gf128mul_4k_lle+0xc1/0x110 [ 194.197269] Read of size 8 at addr ffff888112bd0448 by task kworker/u77:2/899 [ 194.197707] [ 194.197818] CPU: 12 UID: 0 PID: 899 Comm: kworker/u77:2 Not tainted 6.11.0-lku-00028-gfca3ca14a17a-dirty #43 [ 194.198400] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.2-3-gd478f380-prebuilt.qemu.org 04/01/2014 [ 194.199046] Workqueue: smb3decryptd smb2_decrypt_offload [cifs] [ 194.200032] Call Trace: [ 194.200191] <TASK> [ 194.200327] dump_stack_lvl+0x4e/0x70 [ 194.200558] ? gf128mul_4k_lle+0xc1/0x110 [ 194.200809] print_report+0x174/0x505 [ 194.201040] ? __pfx__raw_spin_lock_irqsave+0x10/0x10 [ 194.201352] ? srso_return_thunk+0x5/0x5f [ 194.201604] ? __virt_addr_valid+0xdf/0x1c0 [ 194.201868] ? gf128mul_4k_lle+0xc1/0x110 [ 194.202128] kasan_report+0xc8/0x150 [ 194.202361] ? gf128mul_4k_lle+0xc1/0x110 [ 194.202616] gf128mul_4k_lle+0xc1/0x110 [ 194.202863] ghash_update+0x184/0x210 [ 194.203103] shash_ahash_update+0x184/0x2a0 [ 194.203377] ? __pfx_shash_ahash_update+0x10/0x10 [ 194.203651] ? srso_return_thunk+0x5/0x5f [ 194.203877] ? crypto_gcm_init_common+0x1ba/0x340 [ 194.204142] gcm_hash_assoc_remain_continue+0x10a/0x140 [ 194.204434] crypt_message+0xec1/0x10a0 [cifs] [ 194.206489] ? __pfx_crypt_message+0x10/0x10 [cifs] [ 194.208507] ? srso_return_thunk+0x5/0x5f [ 194.209205] ? srso_return_thunk+0x5/0x5f [ 194.209925] ? srso_return_thunk+0x5/0x5f [ 194.210443] ? srso_return_thunk+0x5/0x5f [ 194.211037] decrypt_raw_data+0x15f/0x250 [cifs] [ 194.212906] ? __pfx_decrypt_raw_data+0x10/0x10 [cifs] [ 194.214670] ? srso_return_thunk+0x5/0x5f [ 194.215193] smb2_decrypt_offload+0x12a/0x6c0 [cifs]
This is because TFM is being used in parallel.
Fix this by allocating a new AEAD TFM for async decryption, but keep the existing one for synchronous READ cases (similar to what is done in smb3_calc_signature()).
Also remove the calls to aead_request_set_callback() and crypto_wait_req() since it's always going to be a synchronous operation.
Signed-off-by: Enzo Matsumiya ematsumiya@suse.de Signed-off-by: Steve French stfrench@microsoft.com [ Anastasia: in old kernels dec and enc fields are named ccmaesdecrypt and ccmaesencrypt. ] Signed-off-by: Anastasia Belova abelova@astralinux.ru --- Backport fix for CVE-2024-50047 fs/cifs/smb2ops.c | 48 +++++++++++++++++++++++++++-------------------- fs/cifs/smb2pdu.c | 6 ++++++ 2 files changed, 34 insertions(+), 20 deletions(-)
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index 68f93de2b152..8cfce01cf699 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -4291,7 +4291,7 @@ smb2_get_enc_key(struct TCP_Server_Info *server, __u64 ses_id, int enc, u8 *key) */ static int crypt_message(struct TCP_Server_Info *server, int num_rqst, - struct smb_rqst *rqst, int enc) + struct smb_rqst *rqst, int enc, struct crypto_aead *tfm) { struct smb2_transform_hdr *tr_hdr = (struct smb2_transform_hdr *)rqst[0].rq_iov[0].iov_base; @@ -4302,8 +4302,6 @@ crypt_message(struct TCP_Server_Info *server, int num_rqst, u8 key[SMB3_ENC_DEC_KEY_SIZE]; struct aead_request *req; u8 *iv; - DECLARE_CRYPTO_WAIT(wait); - struct crypto_aead *tfm; unsigned int crypt_len = le32_to_cpu(tr_hdr->OriginalMessageSize); void *creq;
@@ -4314,15 +4312,6 @@ crypt_message(struct TCP_Server_Info *server, int num_rqst, return rc; }
- rc = smb3_crypto_aead_allocate(server); - if (rc) { - cifs_server_dbg(VFS, "%s: crypto alloc failed\n", __func__); - return rc; - } - - tfm = enc ? server->secmech.ccmaesencrypt : - server->secmech.ccmaesdecrypt; - if ((server->cipher_type == SMB2_ENCRYPTION_AES256_CCM) || (server->cipher_type == SMB2_ENCRYPTION_AES256_GCM)) rc = crypto_aead_setkey(tfm, key, SMB3_GCM256_CRYPTKEY_SIZE); @@ -4361,11 +4350,7 @@ crypt_message(struct TCP_Server_Info *server, int num_rqst, aead_request_set_crypt(req, sg, sg, crypt_len, iv); aead_request_set_ad(req, assoc_data_len);
- aead_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, - crypto_req_done, &wait); - - rc = crypto_wait_req(enc ? crypto_aead_encrypt(req) - : crypto_aead_decrypt(req), &wait); + rc = enc ? crypto_aead_encrypt(req) : crypto_aead_decrypt(req);
if (!rc && enc) memcpy(&tr_hdr->Signature, sign, SMB2_SIGNATURE_SIZE); @@ -4454,7 +4439,7 @@ smb3_init_transform_rq(struct TCP_Server_Info *server, int num_rqst, /* fill the 1st iov with a transform header */ fill_transform_hdr(tr_hdr, orig_len, old_rq, server->cipher_type);
- rc = crypt_message(server, num_rqst, new_rq, 1); + rc = crypt_message(server, num_rqst, new_rq, 1, server->secmech.ccmaesencrypt); cifs_dbg(FYI, "Encrypt message returned %d\n", rc); if (rc) goto err_free; @@ -4480,8 +4465,9 @@ decrypt_raw_data(struct TCP_Server_Info *server, char *buf, unsigned int npages, unsigned int page_data_size, bool is_offloaded) { - struct kvec iov[2]; + struct crypto_aead *tfm; struct smb_rqst rqst = {NULL}; + struct kvec iov[2]; int rc;
iov[0].iov_base = buf; @@ -4496,9 +4482,31 @@ decrypt_raw_data(struct TCP_Server_Info *server, char *buf, rqst.rq_pagesz = PAGE_SIZE; rqst.rq_tailsz = (page_data_size % PAGE_SIZE) ? : PAGE_SIZE;
- rc = crypt_message(server, 1, &rqst, 0); + if (is_offloaded) { + if ((server->cipher_type == SMB2_ENCRYPTION_AES128_GCM) || + (server->cipher_type == SMB2_ENCRYPTION_AES256_GCM)) + tfm = crypto_alloc_aead("gcm(aes)", 0, 0); + else + tfm = crypto_alloc_aead("ccm(aes)", 0, 0); + if (IS_ERR(tfm)) { + rc = PTR_ERR(tfm); + cifs_server_dbg(VFS, "%s: Failed alloc decrypt TFM, rc=%d\n", __func__, rc); + + return rc; + } + } else { + if (unlikely(!server->secmech.ccmaesdecrypt)) + return -EIO; + + tfm = server->secmech.ccmaesdecrypt; + } + + rc = crypt_message(server, 1, &rqst, 0, tfm); cifs_dbg(FYI, "Decrypt message returned %d\n", rc);
+ if (is_offloaded) + crypto_free_aead(tfm); + if (rc) return rc;
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c index 03651cc6b7a5..245e2dd5a194 100644 --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -998,6 +998,12 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses) else cifs_server_dbg(VFS, "Missing expected negotiate contexts\n"); } + + if (server->cipher_type && !rc) { + rc = smb3_crypto_aead_allocate(server); + if (rc) + cifs_server_dbg(VFS, "%s: crypto alloc failed, rc=%d\n", __func__, rc); + } neg_exit: free_rsp_buf(resp_buftype, rsp); return rc;