GHSA-C4R4-Q33M-RP34
Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-14 15:32In the Linux kernel, the following vulnerability has been resolved:
scsi: core: Fill in DMA padding bytes in scsi_alloc_sgtables()
During fuzz testing, the following issue was discovered:
BUG: KMSAN: uninit-value in __dma_map_sg_attrs+0x217/0x310 __dma_map_sg_attrs+0x217/0x310 dma_map_sg_attrs+0x4a/0x70 ata_qc_issue+0x9f8/0x1420 __ata_scsi_queuecmd+0x1657/0x1740 ata_scsi_queuecmd+0x79a/0x920 scsi_queue_rq+0x4472/0x4f40 blk_mq_dispatch_rq_list+0x1cca/0x3ee0 __blk_mq_sched_dispatch_requests+0x458/0x630 blk_mq_sched_dispatch_requests+0x15b/0x340 __blk_mq_run_hw_queue+0xe5/0x250 __blk_mq_delay_run_hw_queue+0x138/0x780 blk_mq_run_hw_queue+0x4bb/0x7e0 blk_mq_sched_insert_request+0x2a7/0x4c0 blk_execute_rq+0x497/0x8a0 sg_io+0xbe0/0xe20 scsi_ioctl+0x2b36/0x3c60 sr_block_ioctl+0x319/0x440 blkdev_ioctl+0x80f/0xd70 __se_sys_ioctl+0x219/0x420 __x64_sys_ioctl+0x93/0xe0 x64_sys_call+0x1d6c/0x3ad0 do_syscall_64+0x4c/0xa0 entry_SYSCALL_64_after_hwframe+0x6e/0xd8
Uninit was created at: __alloc_pages+0x5c0/0xc80 alloc_pages+0xe0e/0x1050 blk_rq_map_user_iov+0x2b77/0x6100 blk_rq_map_user_io+0x2fa/0x4d0 sg_io+0xad6/0xe20 scsi_ioctl+0x2b36/0x3c60 sr_block_ioctl+0x319/0x440 blkdev_ioctl+0x80f/0xd70 __se_sys_ioctl+0x219/0x420 __x64_sys_ioctl+0x93/0xe0 x64_sys_call+0x1d6c/0x3ad0 do_syscall_64+0x4c/0xa0 entry_SYSCALL_64_after_hwframe+0x6e/0xd8
Bytes 14-15 of 16 are uninitialized Memory access of size 16 starts at ffff88800cbdb000
When processing the last unaligned element of the scatterlist, it is supplemented with missing bytes in the amount of pad_len. These bytes remain uninitialized, which leads to a problem.
Extend last_sg->length by pad_len first, then use sg_zero_buffer() to zero those pad_len bytes. sg_zero_buffer() uses sg_miter internally, which correctly handles sg entries spanning multiple pages and padding that crosses a page boundary.
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
{
"affected": [],
"aliases": [
"CVE-2026-89515"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-11T20:19:34Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nscsi: core: Fill in DMA padding bytes in scsi_alloc_sgtables()\n\nDuring fuzz testing, the following issue was discovered:\n\nBUG: KMSAN: uninit-value in __dma_map_sg_attrs+0x217/0x310\n __dma_map_sg_attrs+0x217/0x310\n dma_map_sg_attrs+0x4a/0x70\n ata_qc_issue+0x9f8/0x1420\n __ata_scsi_queuecmd+0x1657/0x1740\n ata_scsi_queuecmd+0x79a/0x920\n scsi_queue_rq+0x4472/0x4f40\n blk_mq_dispatch_rq_list+0x1cca/0x3ee0\n __blk_mq_sched_dispatch_requests+0x458/0x630\n blk_mq_sched_dispatch_requests+0x15b/0x340\n __blk_mq_run_hw_queue+0xe5/0x250\n __blk_mq_delay_run_hw_queue+0x138/0x780\n blk_mq_run_hw_queue+0x4bb/0x7e0\n blk_mq_sched_insert_request+0x2a7/0x4c0\n blk_execute_rq+0x497/0x8a0\n sg_io+0xbe0/0xe20\n scsi_ioctl+0x2b36/0x3c60\n sr_block_ioctl+0x319/0x440\n blkdev_ioctl+0x80f/0xd70\n __se_sys_ioctl+0x219/0x420\n __x64_sys_ioctl+0x93/0xe0\n x64_sys_call+0x1d6c/0x3ad0\n do_syscall_64+0x4c/0xa0\n entry_SYSCALL_64_after_hwframe+0x6e/0xd8\n\nUninit was created at:\n __alloc_pages+0x5c0/0xc80\n alloc_pages+0xe0e/0x1050\n blk_rq_map_user_iov+0x2b77/0x6100\n blk_rq_map_user_io+0x2fa/0x4d0\n sg_io+0xad6/0xe20\n scsi_ioctl+0x2b36/0x3c60\n sr_block_ioctl+0x319/0x440\n blkdev_ioctl+0x80f/0xd70\n __se_sys_ioctl+0x219/0x420\n __x64_sys_ioctl+0x93/0xe0\n x64_sys_call+0x1d6c/0x3ad0\n do_syscall_64+0x4c/0xa0\n entry_SYSCALL_64_after_hwframe+0x6e/0xd8\n\nBytes 14-15 of 16 are uninitialized\nMemory access of size 16 starts at ffff88800cbdb000\n\nWhen processing the last unaligned element of the scatterlist, it is\nsupplemented with missing bytes in the amount of pad_len. These bytes\nremain uninitialized, which leads to a problem.\n\nExtend last_sg-\u003elength by pad_len first, then use sg_zero_buffer() to\nzero those pad_len bytes. sg_zero_buffer() uses sg_miter internally,\nwhich correctly handles sg entries spanning multiple pages and padding\nthat crosses a page boundary.\n\nFound by Linux Verification Center (linuxtesting.org) with Syzkaller.",
"id": "GHSA-c4r4-q33m-rp34",
"modified": "2026-09-14T15:32:27Z",
"published": "2026-09-11T21:31:30Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89515"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1aa6df61cef1f47f503c3ccf60d08c4dd931fdc1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/28ed5343666ff424ce5e248fa1c5a402303b4aff"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/626147717bea776b61ed3631d2c26283760c4cc4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6da140ebdfdd6aa3773945f2c0ebba01d2ef33d8"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6fd1cce5018fdcc8d928e00a6a1dd2997d5b9409"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a4353ec7742bdf87dcdde5875270feb3a1982a51"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e7143c3f4e5c0a7986733c6f27009274bf6c4264"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fd2cbe08c6ccba7fc1ddb830653a93bb7e2d833c"
}
],
"schema_version": "1.4.0",
"severity": []
}
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