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

scsi: ses: Handle enclosure with just a primary component gracefully

This reverts commit 3fe97ff3d949 ("scsi: ses: Don't attach if enclosure has no components") and introduces proper handling of case where there are no detected secondary components, but primary component (enumerated in num_enclosures) does exist. That fix was originally proposed by Ding Hui dinghui@sangfor.com.cn.

Completely ignoring devices that have one primary enclosure and no secondary one results in sesintfadd() bailing completely

scsi 2:0:0:254: enclosure has no enumerated components
    scsi 2:0:0:254: Failed to bind enclosure -12ven in valid configurations such

even on valid configurations with 1 primary and 0 secondary enclosures as below:

# sg_ses /dev/sg0
  3PARdata  SES               3321
Supported diagnostic pages:
  Supported Diagnostic Pages [sdp] [0x0]
  Configuration (SES) [cf] [0x1]
  Short Enclosure Status (SES) [ses] [0x8]
# sg_ses -p cf /dev/sg0
  3PARdata  SES               3321
Configuration diagnostic page:
  number of secondary subenclosures: 0
  generation code: 0x0
  enclosure descriptor list
    Subenclosure identifier: 0 [primary]
      relative ES process id: 0, number of ES processes: 1
      number of type descriptor headers: 1
      enclosure logical identifier (hex): 20000002ac02068d
      enclosure vendor: 3PARdata  product: VV                rev: 3321
  type descriptor header and text list
    Element type: Unspecified, subenclosure id: 0
      number of possible elements: 1

The changelog for the original fix follows

===== We can get a crash when disconnecting the iSCSI session, the call trace like this:

[ffff00002a00fb70] kfree at ffff00000830e224 [ffff00002a00fba0] sesintfremove at ffff000001f200e4 [ffff00002a00fbd0] devicedel at ffff0000086b6a98 [ffff00002a00fc50] deviceunregister at ffff0000086b6d58 [ffff00002a00fc70] __scsiremovedevice at ffff00000870608c [ffff00002a00fca0] scsiremovedevice at ffff000008706134 [ffff00002a00fcc0] __scsiremovetarget at ffff0000087062e4 [ffff00002a00fd10] scsiremovetarget at ffff0000087064c0 [ffff00002a00fd70] _iscsiunbindsession at ffff000001c872c4 [ffff00002a00fdb0] processonework at ffff00000810f35c [ffff00002a00fe00] workerthread at ffff00000810f648 [ffff00002a00fe70] kthread at ffff000008116e98

In sesintfadd, components count could be 0, and kcalloc 0 size scomp, but not saved in edev->component[i].scratch

In this situation, edev->component[0].scratch is an invalid pointer, when kfree it in sesintfremove_enclosure, a crash like above would happen The call trace also could be other random cases when kfree cannot catch the invalid pointer

We should not use edev->component[] array when the components count is 0 We also need check index when use edev->component[] array in

sesenclosuredata_process