cbcvebase.
CVE-2025-38523
published 2025-08-16

CVE-2025-38523: 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…

PriorityP422medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.34%
27.1th percentile
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: __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.

Affected

12 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.12.37-1 (forky)linux 6.12.37-1 (forky)
linuxlinux
linuxlinux>= ee4cdf7ba857a894ad1650d6ab77669cbbfa329e < 87dcc7e33fc3dcb8ed32333cec016528b5bb6ce487dcc7e33fc3dcb8ed32333cec016528b5bb6ce4
linuxlinux>= ee4cdf7ba857a894ad1650d6ab77669cbbfa329e < f0dd353d47f7051afa98c6c60c7486831eb1a410f0dd353d47f7051afa98c6c60c7486831eb1a410
linuxlinux>= ee4cdf7ba857a894ad1650d6ab77669cbbfa329e < 43e7e284fc77b710d899569360ea46fa3374ae2243e7e284fc77b710d899569360ea46fa3374ae22
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel>= 0 < 6.12.37-16.12.37-1
linuxlinux_kernel>= 0 < 6.12.37-16.12.37-1
linuxlinux_kernel>= 6.12 < 6.12.366.12.36
linuxlinux_kernel>= 6.13 < 6.15.86.15.8

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv5.6MEDIUM
vendor_ubuntu5.6MEDIUM
vendor_debian5.5LOW
vendor_redhat5.5MEDIUM
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