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In the Linux kernel, the following vulnerability has been resolved: net: hns3: fix kernel crash when 1588 is received on HIP08 devices The HIP08 devices does not register the ptp devices, so the hdev->ptp is NULL, but the hardware can receive 1588 messages, and set the HNS3_RXD_TS_VLD_B bit, so, if match this case, the access of hdev->ptp->flags will cause a kernel crash: [ 5888.946472] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000018 [ 5888.946475] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000018 ... [ 5889.266118] pc : hclge_ptp_get_rx_hwts+0x40/0x170 [hclge] [ 5889.272612] lr : hclge_ptp_get_rx_hwts+0x34/0x170 [hclge] [ 5889.279101] sp : ffff800012c3bc50 [ 5889.283516] x29: ffff800012c3bc50 x28: ffff2040002be040 [ 5889.289927] x27: ffff800009116484 x26: 0000000080007500 [ 5889.296333] x25: 0000000000000000 x24: ffff204001c6f000 [ 5889.302738] x23: ffff204144f53c00 x22: 0000000000000000 [ 5889.309134] x21: 0000000000000000 x20: ffff204004220080 [ 5889.315520] x19: ffff204144f53c00 x18: 0000000000000000 [ 5889.321897] x17: 0000000000000000 x16: 0000000000000000 [ 5889.328263] x15: 0000004000140ec8 x14: 0000000000000000 [ 5889.334617] x13: 0000000000000000 x12: 00000000010011df [ 5889.340965] x11: bbfeff4d22000000 x10: 0000000000000000 [ 5889.347303] x9 : ffff800009402124 x8 : 0200f78811dfbb4d [ 5889.353637] x7 : 2200000000191b01 x6 : ffff208002a7d480 [ 5889.359959] x5 : 0000000000000000 x4 : 0000000000000000 [ 5889.366271] x3 : 0000000000000000 x2 : 0000000000000000 [ 5889.372567] x1 : 0000000000000000 x0 : ffff20400095c080 [ 5889.378857] Call trace: [ 5889.382285] hclge_ptp_get_rx_hwts+0x40/0x170 [hclge] [ 5889.388304] hns3_handle_bdinfo+0x324/0x410 [hns3] [ 5889.394055] hns3_handle_rx_bd+0x60/0x150 [hns3] [ 5889.399624] hns3_clean_rx_ring+0x84/0x170 [hns3] [ 5889.405270] hns3_nic_common_poll+0xa8/0x220 [hns3] [ 5889.411084] napi_poll+0xcc/0x264 [ 5889.415329] net_rx_action+0xd4/0x21c [ 5889.419911] __do_softirq+0x130/0x358 [ 5889.424484] irq_exit+0x134/0x154 [ 5889.428700] __handle_domain_irq+0x88/0xf0 [ 5889.433684] gic_handle_irq+0x78/0x2c0 [ 5889.438319] el1_irq+0xb8/0x140 [ 5889.442354] arch_cpu_idle+0x18/0x40 [ 5889.446816] default_idle_call+0x5c/0x1c0 [ 5889.451714] cpuidle_idle_call+0x174/0x1b0 [ 5889.456692] do_idle+0xc8/0x160 [ 5889.460717] cpu_startup_entry+0x30/0xfc [ 5889.465523] secondary_start_kernel+0x158/0x1ec [ 5889.470936] Code: 97ffab78 f9411c14 91408294 f9457284 (f9400c80) [ 5889.477950] SMP: stopping secondary CPUs [ 5890.514626] SMP: failed to stop secondary CPUs 0-69,71-95 [ 5890.522951] Starting crashdump kernel...
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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