CVE-2022-49094

In the Linux kernel, the following vulnerability has been resolved:

net/tls: fix slab-out-of-bounds bug in decrypt_internal

The memory size of tls_ctx->rx.iv for AES128-CCM is 12 setting in tls_set_sw_offload(). The return value of crypto_aead_ivsize() for ccm(aes) is 16. So memcpy() require 16 bytes from 12 bytes memory space will trigger slab-out-of-bounds bug as following:

================================================================== BUG: KASAN: slab-out-of-bounds in decrypt_internal+0x385/0xc40 [tls] Read of size 16 at addr ffff888114e84e60 by task tls/10911

Call Trace: dump_stack_lvl+0x34/0x44 print_report.cold+0x5e/0x5db ? decrypt_internal+0x385/0xc40 [tls] kasan_report+0xab/0x120 ? decrypt_internal+0x385/0xc40 [tls] kasan_check_range+0xf9/0x1e0 memcpy+0x20/0x60 decrypt_internal+0x385/0xc40 [tls] ? tls_get_rec+0x2e0/0x2e0 [tls] ? process_rx_list+0x1a5/0x420 [tls] ? tls_setup_from_iter.constprop.0+0x2e0/0x2e0 [tls] decrypt_skb_update+0x9d/0x400 [tls] tls_sw_recvmsg+0x3c8/0xb50 [tls]

Allocated by task 10911: kasan_save_stack+0x1e/0x40 __kasan_kmalloc+0x81/0xa0 tls_set_sw_offload+0x2eb/0xa20 [tls] tls_setsockopt+0x68c/0x700 [tls] __sys_setsockopt+0xfe/0x1b0

Replace the crypto_aead_ivsize() with prot->iv_size + prot->salt_size when memcpy() iv value in TLS_1_3_VERSION scenario.

Weakness

The product reads data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
• To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/540.html

References

• https://git.kernel.org/stable/c/2304660ab6c425df64d95301b601424c6a50f28b
• https://git.kernel.org/stable/c/29be1816cbab9a0dc6243120939fd10a92753756
• https://git.kernel.org/stable/c/2b7d14c105dd8f6412eda5a91e1e6154653731e3
• https://git.kernel.org/stable/c/589154d0f18945f41d138a5b4e49e518d294474b
• https://git.kernel.org/stable/c/6e2f1b033b17dedda51d465861b69e58317d6343
• https://git.kernel.org/stable/c/9381fe8c849cfbe50245ac01fc077554f6eaa0e2