UBUNTU-CVE-2024-26935
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.
02 / AFFECTED SOFTWARE
Affected packages
93 explicit affected versions
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88 explicit affected versions
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34 explicit affected versions
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10 explicit affected versions
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5 explicit affected versions
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37 explicit affected versions
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38 explicit affected versions
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14 explicit affected versions
7 explicit affected versions
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93 explicit affected versions
11 explicit affected versions
33 explicit affected versions
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51 explicit affected versions
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3 explicit affected versions
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51 explicit affected versions
3 explicit affected versions
12 explicit affected versions
37 explicit affected versions
27 explicit affected versions
23 explicit affected versions
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12 explicit affected versions
5 explicit affected versions
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10 explicit affected versions
2 explicit affected versions
13 explicit affected versions
81 explicit affected versions
13 explicit affected versions
45 explicit affected versions
7 explicit affected versions
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10 explicit affected versions
12 explicit affected versions
12 explicit affected versions
80 explicit affected versions
44 explicit affected versions
16 explicit affected versions
3 explicit affected versions
13 explicit affected versions
26 explicit affected versions
37 explicit affected versions
37 explicit affected versions
6 explicit affected versions
14 explicit affected versions
38 explicit affected versions
40 explicit affected versions
9 explicit affected versions
40 explicit affected versions
11 explicit affected versions
48 explicit affected versions
7 explicit affected versions
21 explicit affected versions
52 explicit affected versions
4 explicit affected versions
1 explicit affected versions
46 explicit affected versions
13 explicit affected versions
43 explicit affected versions
46 explicit affected versions
10 explicit affected versions
8 explicit affected versions
1 explicit affected versions
14 explicit affected versions
81 explicit affected versions
4 explicit affected versions
70 explicit affected versions
11 explicit affected versions
1 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
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.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/f23a4d6e07570826fe95023ca1aa96a011fa9f84
- 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://ubuntu.com/security/CVE-2024-26935
- https://ubuntu.com/security/notices/USN-6816-1
- https://ubuntu.com/security/notices/USN-6817-1
- https://ubuntu.com/security/notices/USN-6817-2
- https://ubuntu.com/security/notices/USN-6817-3
- https://ubuntu.com/security/notices/USN-6878-1
- https://ubuntu.com/security/notices/USN-6896-1
- https://ubuntu.com/security/notices/USN-6896-2
- https://ubuntu.com/security/notices/USN-6896-3
- https://ubuntu.com/security/notices/USN-6896-4
- https://ubuntu.com/security/notices/USN-6896-5
- https://ubuntu.com/security/notices/USN-6898-1
- https://ubuntu.com/security/notices/USN-6898-2
- https://ubuntu.com/security/notices/USN-6898-3
- https://ubuntu.com/security/notices/USN-6898-4
- https://ubuntu.com/security/notices/USN-6917-1
- https://ubuntu.com/security/notices/USN-6919-1
- https://ubuntu.com/security/notices/USN-6927-1
- https://ubuntu.com/security/notices/USN-7019-1
- https://www.cve.org/CVERecord?id=CVE-2024-26935