scsi: core: Fix unremoved procfs host directory regression

Summary

In the Linux kernel, the following vulnerability has been resolved: scsi: core: Fix unremoved procfs host directory regression Commit fc663711b944 ("scsi: core: Remove the /proc/scsi/${proc_name} directory earlier") fixed a bug related to modules loading/unloading, by adding a call to scsi_proc_hostdir_rm() on scsi_remove_host(). But that led to a potential duplicate call to the hostdir_rm() routine, since it's also called from scsi_host_dev_release(). That triggered a regression report, which was then fixed by commit be03df3d4bfe ("scsi: core: Fix a procfs host directory removal regression"). The fix just dropped the hostdir_rm() call from dev_release(). But it happens that this proc directory is created on scsi_host_alloc(), and that function "pairs" with scsi_host_dev_release(), while scsi_remove_host() pairs with scsi_add_host(). In other words, it seems the reason for removing the proc directory on dev_release() was meant to cover cases in which a SCSI host structure was allocated, but the call to scsi_add_host() didn't happen. And that pattern happens to exist in some error paths, for example. Syzkaller causes that by using USB raw gadget device, error'ing on usb-storage driver, at usb_stor_probe2(). By checking that path, we can see that the BadDevice label leads to a scsi_host_put() after a SCSI host allocation, but there's no call to scsi_add_host() in such path. That leads to messages like this in dmesg (and a leak of the SCSI host proc structure): usb-storage 4-1:87.51: USB Mass Storage device detected proc_dir_entry 'scsi/usb-storage' already registered WARNING: CPU: 1 PID: 3519 at fs/proc/generic.c:377 proc_register+0x347/0x4e0 fs/proc/generic.c:376 The proper fix seems to still call scsi_proc_hostdir_rm() on dev_release(), but guard that with the state check for SHOST_CREATED; there is even a comment in scsi_host_dev_release() detailing that: such conditional is meant for cases where the SCSI host was allocated but there was no calls to {add,remove}_host(), like the usb-storage case. This is what we propose here and with that, the error path of usb-storage does not trigger the warning anymore.

Timeline

1. May 1, 2024, 5:17 AM UTCCVE published
2. Jun 21, 2024, 2:41 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Oct 15, 2026, 12:39 AM UTCRecord last updated

Affected versions

• Linux Linux

  From 88c3d3bb6469cea929ac68fd326bdcbefcdfdd83 · fixed in 0053f15d50d50c9312d8ab9c11e2e405812dfcac; From 68c665bb185037e7eb66fb792c61da9d7151e99c · fixed in 5c2386ba80e779a92ec3bb64ccadbedd88f779b1; From 2a764d55e938743efa7c2cba7305633bcf227f09 · fixed in cea234bb214b17d004dfdccce4491e6ff57c96ee; From 7e0ae8667fcdd99d1756922e1140cac75f5fa279 · fixed in 3678cf67ff7136db1dd3bf63c361650db5d92889; From be03df3d4bfe7e8866d4aa43d62e648ffe884f5f · fixed in d4c34782b6d7b1e68d18d9549451b19433bd4c6c; From be03df3d4bfe7e8866d4aa43d62e648ffe884f5f · fixed in e293c773c13b830cdc251f155df2254981abc320; From be03df3d4bfe7e8866d4aa43d62e648ffe884f5f · fixed in f4ff08fab66eb5c0b97e1a24edac052fb40bf5d7; From be03df3d4bfe7e8866d4aa43d62e648ffe884f5f · fixed in f23a4d6e07570826fe95023ca1aa96a011fa9f84; From 5.4.238 · fixed in 5.4.274; From 5.10.176 · fixed in 5.10.215; From 5.15.104 · fixed in 5.15.154; From 6.1.21 · fixed in 6.1.84; From 6.2.8 · fixed in 6.3

• Linux Linux

  6.3

• KernelLinux

  fixed in 5.4.274; From 5.5.0 · fixed in 5.10.215; From 5.11.0 · fixed in 5.15.154; From 5.16.0 · fixed in 6.1.84; From 6.2.0 · fixed in 6.6.24; From 6.3.0 · fixed in 6.7.12; From 6.7.0 · fixed in 6.8.3

References 8