CVE-2024-26935: scsi: core: Fix unremoved procfs host directory regression
First published: Wed May 01 2024(Updated: )
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.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| redhat/kernel | <5.4.274 | 5.4.274 |
| redhat/kernel | <5.10.215 | 5.10.215 |
| redhat/kernel | <5.15.154 | 5.15.154 |
| redhat/kernel | <6.1.84 | 6.1.84 |
| redhat/kernel | <6.6.24 | 6.6.24 |
| redhat/kernel | <6.7.12 | 6.7.12 |
| redhat/kernel | <6.8.3 | 6.8.3 |
| redhat/kernel | <6.9 | 6.9 |
| debian/linux | 5.10.223-1 5.10.226-1 6.1.115-1 6.1.119-1 6.12.5-1 6.12.6-1 |
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Reference Links
- https://git.kernel.org/stable/c/0053f15d50d50c9312d8ab9c11e2e405812dfcac
- https://git.kernel.org/stable/c/3678cf67ff7136db1dd3bf63c361650db5d92889
- https://git.kernel.org/stable/c/5c2386ba80e779a92ec3bb64ccadbedd88f779b1
- https://git.kernel.org/stable/c/cea234bb214b17d004dfdccce4491e6ff57c96ee
- https://git.kernel.org/stable/c/d4c34782b6d7b1e68d18d9549451b19433bd4c6c
- https://git.kernel.org/stable/c/e293c773c13b830cdc251f155df2254981abc320
- https://git.kernel.org/stable/c/f23a4d6e07570826fe95023ca1aa96a011fa9f84
- https://git.kernel.org/stable/c/f4ff08fab66eb5c0b97e1a24edac052fb40bf5d7
- https://launchpad.net/bugs/cve/CVE-2024-26935
- https://access.redhat.com/security/cve/CVE-2024-26935
- https://lore.kernel.org/linux-cve-announce/2024050124-CVE-2024-26935-8b4e@gregkh/T
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=2278236
- https://access.redhat.com/errata/RHSA-2024:8617
- https://bugzilla.redhat.com/show_bug.cgi?id=2278235
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-26935
- https://nvd.nist.gov/vuln/detail/CVE-2024-26935
- https://security-tracker.debian.org/tracker/CVE-2024-26935
- https://ubuntu.com/security/CVE-2024-26935
- https://git.kernel.org/linus/f23a4d6e07570826fe95023ca1aa96a011fa9f84
- https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html
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