{"id":"DEBIAN-CVE-2025-38523","details":"In the Linux kernel, the following vulnerability has been resolved:  cifs: Fix the smbd_response slab to allow usercopy  The handling of received data in the smbdirect client code involves using copy_to_iter() to copy data from the smbd_reponse struct's packet trailer to a folioq buffer provided by netfslib that encapsulates a chunk of pagecache.  If, however, CONFIG_HARDENED_USERCOPY=y, this will result in the checks then performed in copy_to_iter() oopsing with something like the following:   CIFS: Attempting to mount //172.31.9.1/test  CIFS: VFS: RDMA transport established  usercopy: Kernel memory exposure attempt detected from SLUB object 'smbd_response_0000000091e24ea1' (offset 81, size 63)!  ------------[ cut here ]------------  kernel BUG at mm/usercopy.c:102!  ...  RIP: 0010:usercopy_abort+0x6c/0x80  ...  Call Trace:   \u003cTASK\u003e   __check_heap_object+0xe3/0x120   __check_object_size+0x4dc/0x6d0   smbd_recv+0x77f/0xfe0 [cifs]   cifs_readv_from_socket+0x276/0x8f0 [cifs]   cifs_read_from_socket+0xcd/0x120 [cifs]   cifs_demultiplex_thread+0x7e9/0x2d50 [cifs]   kthread+0x396/0x830   ret_from_fork+0x2b8/0x3b0   ret_from_fork_asm+0x1a/0x30  The problem is that the smbd_response slab's packet field isn't marked as being permitted for usercopy.  Fix this by passing parameters to kmem_slab_create() to indicate that copy_to_iter() is permitted from the packet region of the smbd_response slab objects, less the header space.","modified":"2026-08-27T23:05:30.138806499Z","published":"2025-08-16T12:15:27.667Z","upstream":["CVE-2025-38523"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2025-38523"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.37-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-38523.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.37-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-38523.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}