linux-stable.git, branch v6.18.26

Linux 6.18.26

2026-04-30T09:13:53+00:00

Signed-off-by: Greg Kroah-Hartman

Buffer overflow in drivers/xen/sys-hypervisor.c

2026-04-30T09:13:53+00:00

commit 27fdbab4221b375de54bf91919798d88520c6e28 upstream.

The build id returned by HYPERVISOR_xen_version(XENVER_build_id) is
neither NUL terminated nor a string.

The first causes a buffer overflow as sprintf in buildid_show will
read and copy till it finds a NUL.

00000000  f4 91 51 f4 dd 38 9e 9d  65 47 52 eb 10 71 db 50  |..Q..8..eGR..q.P|
00000010  b9 a8 01 42 6f 2e 32                              |...Bo.2|
00000017

So use a memcpy instead of sprintf to have the correct value:

00000000  f4 91 51 f4 dd 00 9e 9d  65 47 52 eb 10 71 db 50  |..Q.....eGR..q.P|
00000010  b9 a8 01 42                                       |...B|
00000014

(the above have a hack to embed a zero inside and check it's
returned correctly).

This is XSA-485 / CVE-2026-31786

Fixes: 84b7625728ea ("xen: add sysfs node for hypervisor build id")
Signed-off-by: Frediano Ziglio 
Reviewed-by: Juergen Gross 
Signed-off-by: Juergen Gross 
Signed-off-by: Greg Kroah-Hartman

xen/privcmd: fix double free via VMA splitting

2026-04-30T09:13:53+00:00

commit 24daca4fc07f3ff8cd0e3f629cd982187f48436a upstream.

privcmd_vm_ops defines .close (privcmd_close), but neither .may_split
nor .open. When userspace does a partial munmap() on a privcmd mapping,
the kernel splits the VMA via __split_vma(). Since may_split is NULL,
the split is allowed. vm_area_dup() copies vm_private_data (a pages
array allocated in alloc_empty_pages()) into the new VMA without any
fixup, because there is no .open callback.

Both VMAs now point to the same pages array. When the unmapped portion
is closed, privcmd_close() calls:
    - xen_unmap_domain_gfn_range()
    - xen_free_unpopulated_pages()
    - kvfree(pages)

The surviving VMA still holds the dangling pointer. When it is later
destroyed, the same sequence runs again, which leads to a double free.

Fix this issue by adding a .may_split callback denying the VMA split.

This is XSA-487 / CVE-2026-31787

Fixes: d71f513985c2 ("xen: privcmd: support autotranslated physmap guests.")
Reported-by: Atharva Vartak 
Suggested-by: Atharva Vartak 
Signed-off-by: Juergen Gross 
Reviewed-by: Jan Beulich 
Signed-off-by: Greg Kroah-Hartman

Linux 6.18.25

2026-04-27T13:27:31+00:00

Link: https://lore.kernel.org/r/20260424132430.006424517@linuxfoundation.org
Tested-by: Pavel Machek (CIP) 
Tested-by: Florian Fainelli 
Tested-by: Peter Schneider 
Tested-by: Mark Brown 
Tested-by: Shuah Khan 
Tested-by: Brett A C Sheffield 
Tested-by: Miguel Ojeda 
Tested-by: Wentao Guan 
Tested-by: Dileep Malepu 
Tested-by: Barry K. Nathan 
Signed-off-by: Greg Kroah-Hartman

rxrpc: Fix missing validation of ticket length in non-XDR key preparsing

2026-04-27T13:27:31+00:00

commit ac33733b10b484d666f97688561670afd5861383 upstream.

In rxrpc_preparse(), there are two paths for parsing key payloads: the
XDR path (for large payloads) and the non-XDR path (for payloads <= 28
bytes). While the XDR path (rxrpc_preparse_xdr_rxkad()) correctly
validates the ticket length against AFSTOKEN_RK_TIX_MAX, the non-XDR
path fails to do so.

This allows an unprivileged user to provide a very large ticket length.
When this key is later read via rxrpc_read(), the total
token size (toksize) calculation results in a value that exceeds
AFSTOKEN_LENGTH_MAX, triggering a WARN_ON().

[ 2001.302904] WARNING: CPU: 2 PID: 2108 at net/rxrpc/key.c:778 rxrpc_read+0x109/0x5c0 [rxrpc]

Fix this by adding a check in the non-XDR parsing path of rxrpc_preparse()
to ensure the ticket length does not exceed AFSTOKEN_RK_TIX_MAX,
bringing it into parity with the XDR parsing logic.

Fixes: 8a7a3eb4ddbe ("KEYS: RxRPC: Use key preparsing")
Fixes: 84924aac08a4 ("rxrpc: Fix checker warning")
Reported-by: Anderson Nascimento 
Signed-off-by: Anderson Nascimento 
Signed-off-by: David Howells 
cc: Marc Dionne 
cc: Jeffrey Altman 
cc: Simon Horman 
cc: linux-afs@lists.infradead.org
cc: stable@kernel.org
Link: https://patch.msgid.link/20260422161438.2593376-7-dhowells@redhat.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

crypto: ccp: Don't attempt to copy ID to userspace if PSP command failed

2026-04-27T13:27:31+00:00

commit 4f685dbfa87c546e51d9dc6cab379d20f275e114 upstream.

When retrieving the ID for the CPU, don't attempt to copy the ID blob to
userspace if the firmware command failed.  If the failure was due to an
invalid length, i.e. the userspace buffer+length was too small, copying
the number of bytes _firmware_ requires will overflow the kernel-allocated
buffer and leak data to userspace.

  BUG: KASAN: slab-out-of-bounds in instrument_copy_to_user ../include/linux/instrumented.h:129 [inline]
  BUG: KASAN: slab-out-of-bounds in _inline_copy_to_user ../include/linux/uaccess.h:205 [inline]
  BUG: KASAN: slab-out-of-bounds in _copy_to_user+0x66/0xa0 ../lib/usercopy.c:26
  Read of size 64 at addr ffff8881867f5960 by task syz.0.906/24388

  CPU: 130 UID: 0 PID: 24388 Comm: syz.0.906 Tainted: G     U     O        7.0.0-smp-DEV #28 PREEMPTLAZY
  Tainted: [U]=USER, [O]=OOT_MODULE
  Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 12.62.0-0 11/19/2025
  Call Trace:
   
   dump_stack_lvl+0xc5/0x110 ../lib/dump_stack.c:120
   print_address_description ../mm/kasan/report.c:378 [inline]
   print_report+0xbc/0x260 ../mm/kasan/report.c:482
   kasan_report+0xa2/0xe0 ../mm/kasan/report.c:595
   check_region_inline ../mm/kasan/generic.c:-1 [inline]
   kasan_check_range+0x264/0x2c0 ../mm/kasan/generic.c:200
   instrument_copy_to_user ../include/linux/instrumented.h:129 [inline]
   _inline_copy_to_user ../include/linux/uaccess.h:205 [inline]
   _copy_to_user+0x66/0xa0 ../lib/usercopy.c:26
   copy_to_user ../include/linux/uaccess.h:236 [inline]
   sev_ioctl_do_get_id2+0x361/0x490 ../drivers/crypto/ccp/sev-dev.c:2222
   sev_ioctl+0x25f/0x490 ../drivers/crypto/ccp/sev-dev.c:2575
   vfs_ioctl ../fs/ioctl.c:51 [inline]
   __do_sys_ioctl ../fs/ioctl.c:597 [inline]
   __se_sys_ioctl+0x11d/0x1b0 ../fs/ioctl.c:583
   do_syscall_x64 ../arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0xe0/0x800 ../arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x76/0x7e
   

WARN if the driver says the command succeeded, but the firmware error code
says otherwise, as __sev_do_cmd_locked() is expected to return -EIO on any
firwmware error.

Reported-by: Alexander Potapenko 
Reported-by: Sebastian Alba Vives 
Fixes: d6112ea0cb34 ("crypto: ccp - introduce SEV_GET_ID2 command")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson 
Signed-off-by: Herbert Xu 
Signed-off-by: Greg Kroah-Hartman

crypto: ccp: Don't attempt to copy PDH cert to userspace if PSP command failed

2026-04-27T13:27:31+00:00

commit e76239fed3cffd6d304d8ca3ce23984fd24f57d3 upstream.

When retrieving the PDH cert, don't attempt to copy the blobs to userspace
if the firmware command failed.  If the failure was due to an invalid
length, i.e. the userspace buffer+length was too small, copying the number
of bytes _firmware_ requires will overflow the kernel-allocated buffer and
leak data to userspace.

  BUG: KASAN: slab-out-of-bounds in instrument_copy_to_user ../include/linux/instrumented.h:129 [inline]
  BUG: KASAN: slab-out-of-bounds in _inline_copy_to_user ../include/linux/uaccess.h:205 [inline]
  BUG: KASAN: slab-out-of-bounds in _copy_to_user+0x66/0xa0 ../lib/usercopy.c:26
  Read of size 2084 at addr ffff8885c4ab8aa0 by task syz.0.186/21033

  CPU: 51 UID: 0 PID: 21033 Comm: syz.0.186 Tainted: G     U     O        7.0.0-smp-DEV #28 PREEMPTLAZY
  Tainted: [U]=USER, [O]=OOT_MODULE
  Hardware name: Google, Inc.                                                       Arcadia_IT_80/Arcadia_IT_80, BIOS 34.84.12-0 11/17/2025
  Call Trace:
   
   dump_stack_lvl+0xc5/0x110 ../lib/dump_stack.c:120
   print_address_description ../mm/kasan/report.c:378 [inline]
   print_report+0xbc/0x260 ../mm/kasan/report.c:482
   kasan_report+0xa2/0xe0 ../mm/kasan/report.c:595
   check_region_inline ../mm/kasan/generic.c:-1 [inline]
   kasan_check_range+0x264/0x2c0 ../mm/kasan/generic.c:200
   instrument_copy_to_user ../include/linux/instrumented.h:129 [inline]
   _inline_copy_to_user ../include/linux/uaccess.h:205 [inline]
   _copy_to_user+0x66/0xa0 ../lib/usercopy.c:26
   copy_to_user ../include/linux/uaccess.h:236 [inline]
   sev_ioctl_do_pdh_export+0x3d3/0x7c0 ../drivers/crypto/ccp/sev-dev.c:2347
   sev_ioctl+0x2a2/0x490 ../drivers/crypto/ccp/sev-dev.c:2568
   vfs_ioctl ../fs/ioctl.c:51 [inline]
   __do_sys_ioctl ../fs/ioctl.c:597 [inline]
   __se_sys_ioctl+0x11d/0x1b0 ../fs/ioctl.c:583
   do_syscall_x64 ../arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0xe0/0x800 ../arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x76/0x7e
   

WARN if the driver says the command succeeded, but the firmware error code
says otherwise, as __sev_do_cmd_locked() is expected to return -EIO on any
firwmware error.

Reported-by: Alexander Potapenko 
Reported-by: Sebastian Alba Vives 
Fixes: 76a2b524a4b1 ("crypto: ccp: Implement SEV_PDH_CERT_EXPORT ioctl command")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson 
Signed-off-by: Herbert Xu 
Signed-off-by: Greg Kroah-Hartman

crypto: ccp: Don't attempt to copy CSR to userspace if PSP command failed

2026-04-27T13:27:31+00:00

commit abe4a6d6f606113251868c2c4a06ba904bb41eed upstream.

When retrieving the PEK CSR, don't attempt to copy the blob to userspace
if the firmware command failed.  If the failure was due to an invalid
length, i.e. the userspace buffer+length was too small, copying the number
of bytes _firmware_ requires will overflow the kernel-allocated buffer and
leak data to userspace.

  BUG: KASAN: slab-out-of-bounds in instrument_copy_to_user ../include/linux/instrumented.h:129 [inline]
  BUG: KASAN: slab-out-of-bounds in _inline_copy_to_user ../include/linux/uaccess.h:205 [inline]
  BUG: KASAN: slab-out-of-bounds in _copy_to_user+0x66/0xa0 ../lib/usercopy.c:26
  Read of size 2084 at addr ffff898144612e20 by task syz.9.219/21405

  CPU: 14 UID: 0 PID: 21405 Comm: syz.9.219 Tainted: G     U     O        7.0.0-smp-DEV #28 PREEMPTLAZY
  Tainted: [U]=USER, [O]=OOT_MODULE
  Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 12.62.0-0 11/19/2025
  Call Trace:
   
   dump_stack_lvl+0xc5/0x110 ../lib/dump_stack.c:120
   print_address_description ../mm/kasan/report.c:378 [inline]
   print_report+0xbc/0x260 ../mm/kasan/report.c:482
   kasan_report+0xa2/0xe0 ../mm/kasan/report.c:595
   check_region_inline ../mm/kasan/generic.c:-1 [inline]
   kasan_check_range+0x264/0x2c0 ../mm/kasan/generic.c:200
   instrument_copy_to_user ../include/linux/instrumented.h:129 [inline]
   _inline_copy_to_user ../include/linux/uaccess.h:205 [inline]
   _copy_to_user+0x66/0xa0 ../lib/usercopy.c:26
   copy_to_user ../include/linux/uaccess.h:236 [inline]
   sev_ioctl_do_pek_csr+0x31f/0x590 ../drivers/crypto/ccp/sev-dev.c:1872
   sev_ioctl+0x3a4/0x490 ../drivers/crypto/ccp/sev-dev.c:2562
   vfs_ioctl ../fs/ioctl.c:51 [inline]
   __do_sys_ioctl ../fs/ioctl.c:597 [inline]
   __se_sys_ioctl+0x11d/0x1b0 ../fs/ioctl.c:583
   do_syscall_x64 ../arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0xe0/0x800 ../arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x76/0x7e
   

WARN if the driver says the command succeeded, but the firmware error code
says otherwise, as __sev_do_cmd_locked() is expected to return -EIO on any
firwmware error.

Reported-by: Alexander Potapenko 
Reported-by: Sebastian Alba Vives 
Fixes: e799035609e1 ("crypto: ccp: Implement SEV_PEK_CSR ioctl command")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson 
Signed-off-by: Herbert Xu 
Signed-off-by: Greg Kroah-Hartman

net/packet: fix TOCTOU race on mmap'd vnet_hdr in tpacket_snd()

2026-04-27T13:27:31+00:00

commit 2c054e17d9d41f1020376806c7f750834ced4dc5 upstream.

In tpacket_snd(), when PACKET_VNET_HDR is enabled, vnet_hdr points
directly into the mmap'd TX ring buffer shared with userspace. The
kernel validates the header via __packet_snd_vnet_parse() but then
re-reads all fields later in virtio_net_hdr_to_skb(). A concurrent
userspace thread can modify the vnet_hdr fields between validation
and use, bypassing all safety checks.

The non-TPACKET path (packet_snd()) already correctly copies vnet_hdr
to a stack-local variable. All other vnet_hdr consumers in the kernel
(tun.c, tap.c, virtio_net.c) also use stack copies. The TPACKET TX
path is the only caller of virtio_net_hdr_to_skb() that reads directly
from user-controlled shared memory.

Fix this by copying vnet_hdr from the mmap'd ring buffer to a
stack-local variable before validation and use, consistent with the
approach used in packet_snd() and all other callers.

Fixes: 1d036d25e560 ("packet: tpacket_snd gso and checksum offload")
Signed-off-by: Bingquan Chen 
Reviewed-by: Willem de Bruijn 
Link: https://patch.msgid.link/20260418112006.78823-1-patzilla007@gmail.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

ALSA: caiaq: take a reference on the USB device in create_card()

2026-04-27T13:27:31+00:00

commit 80bb50e2d459213cccff3111d5ef98ed4238c0d5 upstream.

The caiaq driver stores a pointer to the parent USB device in
cdev->chip.dev but never takes a reference on it. The card's
private_free callback, snd_usb_caiaq_card_free(), can run
asynchronously via snd_card_free_when_closed() after the USB
device has already been disconnected and freed, so any access to
cdev->chip.dev in that path dereferences a freed usb_device.

On top of the refcounting issue, the current card_free implementation
calls usb_reset_device(cdev->chip.dev). A reset in a free callback
is inappropriate: the device is going away, the call takes the
device lock in a teardown context, and the reset races with the
disconnect path that the callback is already cleaning up after.

Take a reference on the USB device in create_card() with
usb_get_dev(), drop it with usb_put_dev() in the free callback,
and remove the usb_reset_device() call.

Fixes: b04dcbb7f7b1 ("ALSA: caiaq: Use snd_card_free_when_closed() at disconnection")
Cc: stable@vger.kernel.org
Cc: Andrey Konovalov 
Signed-off-by: Berk Cem Goksel 
Link: https://patch.msgid.link/20260413034941.1131465-3-berkcgoksel@gmail.com
Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman