55%
18%
60%
In the Linux kernel, the following vulnerability has been resolved: net/smc: fix lacks of icsk_syn_mss with IPPROTO_SMC Eric report a panic on IPPROTO_SMC, and give the facts that when INET_PROTOSW_ICSK was set, icsk->icsk_sync_mss must be set too. Bug: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 Mem abort info: ESR = 0x0000000086000005 EC = 0x21: IABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x05: level 1 translation fault user pgtable: 4k pages, 48-bit VAs, pgdp=00000001195d1000 [0000000000000000] pgd=0800000109c46003, p4d=0800000109c46003, pud=0000000000000000 Internal error: Oops: 0000000086000005 [#1] PREEMPT SMP Modules linked in: CPU: 1 UID: 0 PID: 8037 Comm: syz.3.265 Not tainted 6.11.0-rc7-syzkaller-g5f5673607153 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024 pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : 0x0 lr : cipso_v4_sock_setattr+0x2a8/0x3c0 net/ipv4/cipso_ipv4.c:1910 sp : ffff80009b887a90 x29: ffff80009b887aa0 x28: ffff80008db94050 x27: 0000000000000000 x26: 1fffe0001aa6f5b3 x25: dfff800000000000 x24: ffff0000db75da00 x23: 0000000000000000 x22: ffff0000d8b78518 x21: 0000000000000000 x20: ffff0000d537ad80 x19: ffff0000d8b78000 x18: 1fffe000366d79ee x17: ffff8000800614a8 x16: ffff800080569b84 x15: 0000000000000001 x14: 000000008b336894 x13: 00000000cd96feaa x12: 0000000000000003 x11: 0000000000040000 x10: 00000000000020a3 x9 : 1fffe0001b16f0f1 x8 : 0000000000000000 x7 : 0000000000000000 x6 : 000000000000003f x5 : 0000000000000040 x4 : 0000000000000001 x3 : 0000000000000000 x2 : 0000000000000002 x1 : 0000000000000000 x0 : ffff0000d8b78000 Call trace: 0x0 netlbl_sock_setattr+0x2e4/0x338 net/netlabel/netlabel_kapi.c:1000 smack_netlbl_add+0xa4/0x154 security/smack/smack_lsm.c:2593 smack_socket_post_create+0xa8/0x14c security/smack/smack_lsm.c:2973 security_socket_post_create+0x94/0xd4 security/security.c:4425 __sock_create+0x4c8/0x884 net/socket.c:1587 sock_create net/socket.c:1622 [inline] __sys_socket_create net/socket.c:1659 [inline] __sys_socket+0x134/0x340 net/socket.c:1706 __do_sys_socket net/socket.c:1720 [inline] __se_sys_socket net/socket.c:1718 [inline] __arm64_sys_socket+0x7c/0x94 net/socket.c:1718 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598 Code: ???????? ???????? ???????? ???????? (????????) ---[ end trace 0000000000000000 ]--- This patch add a toy implementation that performs a simple return to prevent such panic. This is because MSS can be set in sock_create_kern or smc_setsockopt, similar to how it's done in AF_SMC. However, for AF_SMC, there is currently no way to synchronize MSS within __sys_connect_file. This toy implementation lays the groundwork for us to support such feature for IPPROTO_SMC in the future.
CVSS 3.1 Base Score 5.5. CVSS Attack Vector: local. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
While there are no complete fixes aside from conscientious programming, the following steps will go a long way to ensure that NULL pointer dereferences do not occur.
}
/* make use of pointer1 *//* ... */If you are working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the if statement; and unlock when it has finished.
This example takes an IP address from a user, verifies that it is well formed and then looks up the hostname and copies it into a buffer.
}
strcpy(hostname, hp->h_name);/*routine that ensures user_supplied_addr is in the right format for conversion */If an attacker provides an address that appears to be well-formed, but the address does not resolve to a hostname, then the call to gethostbyaddr() will return NULL. Since the code does not check the return value from gethostbyaddr (CWE-252), a NULL pointer dereference would then occur in the call to strcpy().
Note that this example is also vulnerable to a buffer overflow (see CWE-119).
In the following code, the programmer assumes that the system always has a property named "cmd" defined. If an attacker can control the program's environment so that "cmd" is not defined, the program throws a NULL pointer exception when it attempts to call the trim() method.
cmd = cmd.trim();This application has registered to handle a URL when sent an intent:
}......
}
}int length = URL.length();...The application assumes the URL will always be included in the intent. When the URL is not present, the call to getStringExtra() will return null, thus causing a null pointer exception when length() is called.
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