CVE-2023-53246

Description

In the Linux kernel, the following vulnerability has been resolved:cifs: fix DFS traversal oops without CONFIG_CIFS_DFS_UPCALLWhen compiled with CONFIG_CIFS_DFS_UPCALL disabled, cifs_dfs_d_automountis null. cifs.ko logic for mapping CIFS_FATTR_DFS_REFERRAL attributes toS_AUTOMOUNT and corresponding dentry flags is retained regardless ofCONFIG_CIFS_DFS_UPCALL, leading to a null pointer dereference inVFS follow_automount() when traversing a DFS referral link: BUG: kernel null pointer dereference, address: 0000000000000000 ... Call Trace: __traverse_mounts+0xb5/0x220 cifs_revalidate_mapping+0x65/0xc0 [cifs] step_into+0x195/0x610 lookup_fast+0xe2/0xf0 path_lookupat+0x64/0x140 filename_lookup+0xc2/0x140 __create_object+0x299/0x380 kmem_cache_alloc+0x119/0x220 user_path_at_empty+0x31/0x50 user_path_at_empty+0x31/0x50 __x64_sys_chdir+0x2a/0xd0 exit_to_user_mode_prepare+0xca/0x100 do_syscall_64+0x42/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdcThis fix adds an inline cifs_dfs_d_automount() {return -EREMOTE} handlerwhen CONFIG_CIFS_DFS_UPCALL is disabled. An alternative would be toavoid flagging S_AUTOMOUNT, etc. without CONFIG_CIFS_DFS_UPCALL. Thisapproach was chosen as it provides more control over the error path.

Risk Information

Base Score

5.5

MODERATE

Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Score

Exploitation Probability

0.017

Associated Vulnerability

No records found

Patch Details

No records found

References

https://nvd.nist.gov/vuln/detail/CVE-2023-1234
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-1234