ghsa-jvcg-848p-wjgf
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
nbd: fix incomplete validation of ioctl arg
We tested and found an alarm caused by nbd_ioctl arg without verification. The UBSAN warning calltrace like below:
UBSAN: Undefined behaviour in fs/buffer.c:1709:35 signed integer overflow: -9223372036854775808 - 1 cannot be represented in type 'long long int' CPU: 3 PID: 2523 Comm: syz-executor.0 Not tainted 4.19.90 #1 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x0/0x3f0 arch/arm64/kernel/time.c:78 show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158 __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x170/0x1dc lib/dump_stack.c:118 ubsan_epilogue+0x18/0xb4 lib/ubsan.c:161 handle_overflow+0x188/0x1dc lib/ubsan.c:192 __ubsan_handle_sub_overflow+0x34/0x44 lib/ubsan.c:206 __block_write_full_page+0x94c/0xa20 fs/buffer.c:1709 block_write_full_page+0x1f0/0x280 fs/buffer.c:2934 blkdev_writepage+0x34/0x40 fs/block_dev.c:607 __writepage+0x68/0xe8 mm/page-writeback.c:2305 write_cache_pages+0x44c/0xc70 mm/page-writeback.c:2240 generic_writepages+0xdc/0x148 mm/page-writeback.c:2329 blkdev_writepages+0x2c/0x38 fs/block_dev.c:2114 do_writepages+0xd4/0x250 mm/page-writeback.c:2344
The reason for triggering this warning is __block_write_full_page() -> i_size_read(inode) - 1 overflow. inode->i_size is assigned in __nbd_ioctl() -> nbd_set_size() -> bytesize. We think it is necessary to limit the size of arg to prevent errors.
Moreover, __nbd_ioctl() -> nbd_add_socket(), arg will be cast to int. Assuming the value of arg is 0x80000000000000001) (on a 64-bit machine), it will become 1 after the coercion, which will return unexpected results.
Fix it by adding checks to prevent passing in too large numbers.
{
"affected": [],
"aliases": [
"CVE-2023-53513"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-10-01T12:15:55Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnbd: fix incomplete validation of ioctl arg\n\nWe tested and found an alarm caused by nbd_ioctl arg without verification.\nThe UBSAN warning calltrace like below:\n\nUBSAN: Undefined behaviour in fs/buffer.c:1709:35\nsigned integer overflow:\n-9223372036854775808 - 1 cannot be represented in type \u0027long long int\u0027\nCPU: 3 PID: 2523 Comm: syz-executor.0 Not tainted 4.19.90 #1\nHardware name: linux,dummy-virt (DT)\nCall trace:\n dump_backtrace+0x0/0x3f0 arch/arm64/kernel/time.c:78\n show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158\n __dump_stack lib/dump_stack.c:77 [inline]\n dump_stack+0x170/0x1dc lib/dump_stack.c:118\n ubsan_epilogue+0x18/0xb4 lib/ubsan.c:161\n handle_overflow+0x188/0x1dc lib/ubsan.c:192\n __ubsan_handle_sub_overflow+0x34/0x44 lib/ubsan.c:206\n __block_write_full_page+0x94c/0xa20 fs/buffer.c:1709\n block_write_full_page+0x1f0/0x280 fs/buffer.c:2934\n blkdev_writepage+0x34/0x40 fs/block_dev.c:607\n __writepage+0x68/0xe8 mm/page-writeback.c:2305\n write_cache_pages+0x44c/0xc70 mm/page-writeback.c:2240\n generic_writepages+0xdc/0x148 mm/page-writeback.c:2329\n blkdev_writepages+0x2c/0x38 fs/block_dev.c:2114\n do_writepages+0xd4/0x250 mm/page-writeback.c:2344\n\nThe reason for triggering this warning is __block_write_full_page()\n-\u003e i_size_read(inode) - 1 overflow.\ninode-\u003ei_size is assigned in __nbd_ioctl() -\u003e nbd_set_size() -\u003e bytesize.\nWe think it is necessary to limit the size of arg to prevent errors.\n\nMoreover, __nbd_ioctl() -\u003e nbd_add_socket(), arg will be cast to int.\nAssuming the value of arg is 0x80000000000000001) (on a 64-bit machine),\nit will become 1 after the coercion, which will return unexpected results.\n\nFix it by adding checks to prevent passing in too large numbers.",
"id": "GHSA-jvcg-848p-wjgf",
"modified": "2025-10-01T12:30:31Z",
"published": "2025-10-01T12:30:30Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-53513"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/52851d0c3354b397c11d31dfeb8b2a2fc85a0002"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/55793ea54d77719a071b1ccc05a05056e3b5e009"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fab766c8a1aff715bce7075aab40e780266f8e1a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ffb75ffaa68723276365d0f9d00b03362b750657"
}
],
"schema_version": "1.4.0",
"severity": []
}
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