CVE-2026-89515

scsi: core: Fill in DMA padding bytes in scsi_alloc_sgtables()

State: Published
Severity: Not scored
Published: Sep 11, 2026
Updated: Oct 19, 2026
Reserved: Sep 11, 2026

Description

In 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.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	40b01b9bbdf51ae543a04744283bf2d56c4a6afa to before 1aa6df61cef1f47f503c3ccf60d08c4dd931fdc1Affected 40b01b9bbdf51ae543a04744283bf2d56c4a6afa to before 6da140ebdfdd6aa3773945f2c0ebba01d2ef33d8Affected 40b01b9bbdf51ae543a04744283bf2d56c4a6afa to before fd2cbe08c6ccba7fc1ddb830653a93bb7e2d833cAffected 40b01b9bbdf51ae543a04744283bf2d56c4a6afa to before 28ed5343666ff424ce5e248fa1c5a402303b4affAffected 40b01b9bbdf51ae543a04744283bf2d56c4a6afa to before a4353ec7742bdf87dcdde5875270feb3a1982a51Affected 40b01b9bbdf51ae543a04744283bf2d56c4a6afa to before e7143c3f4e5c0a7986733c6f27009274bf6c4264Affected 40b01b9bbdf51ae543a04744283bf2d56c4a6afa to before 6fd1cce5018fdcc8d928e00a6a1dd2997d5b9409Affected 40b01b9bbdf51ae543a04744283bf2d56c4a6afa to before 626147717bea776b61ed3631d2c26283760c4cc4Affected
LinuxLinux	2.6.25Affected before 2.6.25Not affected 5.10.270 through 5.10.Not affected 5.15.221 through 5.15.Not affected 6.1.188 through 6.1.Not affected 6.6.157 through 6.6.Not affected 6.12.109 through 6.12.Not affected 6.18.50 through 6.18.Not affected 7.2.4 through 7.2.*Not affected 7.3 and laterNot affected

Product

Versions

LinuxLinux

40b01b9bbdf51ae543a04744283bf2d56c4a6afa to before 1aa6df61cef1f47f503c3ccf60d08c4dd931fdc1Affected
40b01b9bbdf51ae543a04744283bf2d56c4a6afa to before 6da140ebdfdd6aa3773945f2c0ebba01d2ef33d8Affected
40b01b9bbdf51ae543a04744283bf2d56c4a6afa to before fd2cbe08c6ccba7fc1ddb830653a93bb7e2d833cAffected
40b01b9bbdf51ae543a04744283bf2d56c4a6afa to before 28ed5343666ff424ce5e248fa1c5a402303b4affAffected
40b01b9bbdf51ae543a04744283bf2d56c4a6afa to before a4353ec7742bdf87dcdde5875270feb3a1982a51Affected
40b01b9bbdf51ae543a04744283bf2d56c4a6afa to before e7143c3f4e5c0a7986733c6f27009274bf6c4264Affected
40b01b9bbdf51ae543a04744283bf2d56c4a6afa to before 6fd1cce5018fdcc8d928e00a6a1dd2997d5b9409Affected
40b01b9bbdf51ae543a04744283bf2d56c4a6afa to before 626147717bea776b61ed3631d2c26283760c4cc4Affected

LinuxLinux

2.6.25Affected
before 2.6.25Not affected
5.10.270 through 5.10.*Not affected
5.15.221 through 5.15.*Not affected
6.1.188 through 6.1.*Not affected
6.6.157 through 6.6.*Not affected
6.12.109 through 6.12.*Not affected
6.18.50 through 6.18.*Not affected
7.2.4 through 7.2.*Not affected
7.3 and laterNot affected

References

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