CVE-2021-47375

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Source
https://cve.org/CVERecord?id=CVE-2021-47375
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-47375.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2021-47375
Downstream
Related
Published
2024-05-21T15:15:23Z
Modified
2026-03-15T21:45:12Z
Severity
  • 6.2 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N CVSS Calculator
Summary
[none]
Details

In the Linux kernel, the following vulnerability has been resolved:

blktrace: Fix uaf in blk_trace access after removing by sysfs

There is an use-after-free problem triggered by following process:

  P1(sda)				P2(sdb)
		echo 0 > /sys/block/sdb/trace/enable
		  blk_trace_remove_queue
		    synchronize_rcu
		    blk_trace_free
		      relay_close

rcu_read_lock __blk_add_trace trace_note_tsk (Iterate running_trace_list) relay_close_buf relay_destroy_buf kfree(buf) trace_note(sdb's bt) relay_reserve buf->offset <- nullptr deference (use-after-free) !!! rcu_read_unlock

[ 502.714379] BUG: kernel NULL pointer dereference, address: 0000000000000010 [ 502.715260] #PF: supervisor read access in kernel mode [ 502.715903] #PF: error_code(0x0000) - not-present page [ 502.716546] PGD 103984067 P4D 103984067 PUD 17592b067 PMD 0 [ 502.717252] Oops: 0000 [#1] SMP [ 502.720308] RIP: 0010:trace_note.isra.0+0x86/0x360 [ 502.732872] Call Trace: [ 502.733193] __blk_add_trace.cold+0x137/0x1a3 [ 502.733734] blk_add_trace_rq+0x7b/0xd0 [ 502.734207] blk_add_trace_rq_issue+0x54/0xa0 [ 502.734755] blk_mq_start_request+0xde/0x1b0 [ 502.735287] scsi_queue_rq+0x528/0x1140 ... [ 502.742704] sg_new_write.isra.0+0x16e/0x3e0 [ 502.747501] sg_ioctl+0x466/0x1100

Reproduce method: ioctl(/dev/sda, BLKTRACESETUP, blk_user_trace_setup[buf_size=127]) ioctl(/dev/sda, BLKTRACESTART) ioctl(/dev/sdb, BLKTRACESETUP, blk_user_trace_setup[buf_size=127]) ioctl(/dev/sdb, BLKTRACESTART)

echo 0 > /sys/block/sdb/trace/enable & // Add delay(mdelay/msleep) before kernel enters blk_trace_free()

ioctl$SG_IO(/dev/sda, SG_IO, ...) // Enters trace_note_tsk() after blk_trace_free() returned // Use mdelay in rcu region rather than msleep(which may schedule out)

Remove blk_trace from running_list before calling blk_trace_free() by sysfs if blk_trace is at Blktrace_running state.

References

Affected packages

Git /

Affected ranges

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-47375.json"
unresolved_ranges 
[
    {
        "events": [
            {
                "introduced": "2.6.30"
            },
            {
                "fixed": "4.4.286"
            }
        ]
    },
    {
        "events": [
            {
                "introduced": "4.5"
            },
            {
                "fixed": "4.9.285"
            }
        ]
    },
    {
        "events": [
            {
                "introduced": "4.10"
            },
            {
                "fixed": "4.14.249"
            }
        ]
    },
    {
        "events": [
            {
                "introduced": "4.15"
            },
            {
                "fixed": "4.19.209"
            }
        ]
    },
    {
        "events": [
            {
                "introduced": "4.20"
            },
            {
                "fixed": "5.4.150"
            }
        ]
    },
    {
        "events": [
            {
                "introduced": "5.5"
            },
            {
                "fixed": "5.10.70"
            }
        ]
    },
    {
        "events": [
            {
                "introduced": "5.11"
            },
            {
                "fixed": "5.14.9"
            }
        ]
    },
    {
        "events": [
            {
                "introduced": "0"
            },
            {
                "last_affected": "5.15-rc1"
            }
        ]
    },
    {
        "events": [
            {
                "introduced": "0"
            },
            {
                "last_affected": "5.15-rc2"
            }
        ]
    }
]