6.2

CVE-2021-47375

blktrace: Fix uaf in blk_trace access after removing by sysfs

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.
Daten sind bereitgestellt durch National Vulnerability Database (NVD)
Linux ≫ Linux Kernel Version >= 2.6.30 < 4.4.286
Linux ≫ Linux Kernel Version >= 4.5 < 4.9.285
Linux ≫ Linux Kernel Version >= 4.10 < 4.14.249
Linux ≫ Linux Kernel Version >= 4.15 < 4.19.209
Linux ≫ Linux Kernel Version >= 4.20 < 5.4.150
Linux ≫ Linux Kernel Version >= 5.5 < 5.10.70
Linux ≫ Linux Kernel Version >= 5.11 < 5.14.9
Linux ≫ Linux Kernel Version5.15 Updaterc1
Linux ≫ Linux Kernel Version5.15 Updaterc2
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Zu dieser CVE wurde keine Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.25% 0.164
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
134c704f-9b21-4f2e-91b3-4a467353bcc0 6.2 2.5 3.6
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CWE-416 Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

https://git.kernel.org/stable/c/3815fe7371d2411ce164281cef40d9fc7b323dee
Patch
https://git.kernel.org/stable/c/488da313edf3abea7f7733efe011c96b23740ab5
Patch
https://git.kernel.org/stable/c/5afedf670caf30a2b5a52da96eb7eac7dee6a9c9
Patch
https://git.kernel.org/stable/c/677e362ba807f3aafe6f405c07e0b37244da5222
Patch
https://git.kernel.org/stable/c/a5f8e86192612d0183047448d8bbe7918b3f1a26
Patch
https://git.kernel.org/stable/c/d56171d9360c0170c5c5f8f7e2362a2e999eca40
Patch
https://git.kernel.org/stable/c/dacfd5e4d1142bfb3809aab3634a375f6f373269
Patch
https://git.kernel.org/stable/c/ebb8d26d93c3ec3c7576c52a8373a2309423c069
Patch