net: mana: Fix crash from unvalidated SHM offset read from BAR0 during FLRdavem/net

During Function Level Reset recovery, the MANA driver reads
hardware BAR0 registers that may temporarily contain garbage values.
The SHM (Shared Memory) offset read from GDMA_REG_SHM_OFFSET is used
to compute gc->shm_base, which is later dereferenced via readl() in
mana_smc_poll_register(). If the hardware returns an unaligned or
out-of-range value, the driver must not blindly use it, as this would
propagate the hardware error into a kernel crash.

The following crash was observed on an arm64 Hyper-V guest running
kernel 6.17.0-3013-azure during VF reset recovery triggered by HWC
timeout.

[13291.785274] Unable to handle kernel paging request at virtual address ffff8000a200001b
[13291.785311] Mem abort info:
[13291.785332]   ESR = 0x0000000096000021
[13291.785343]   EC = 0x25: DABT (current EL), IL = 32 bits
[13291.785355]   SET = 0, FnV = 0
[13291.785363]   EA = 0, S1PTW = 0
[13291.785372]   FSC = 0x21: alignment fault
[13291.785382] Data abort info:
[13291.785391]   ISV = 0, ISS = 0x00000021, ISS2 = 0x00000000
[13291.785404]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[13291.785412]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[13291.785421] swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000014df3a1000
[13291.785432] [ffff8000a200001b] pgd=1000000100438403, p4d=1000000100438403, pud=1000000100439403, pmd=0068000fc2000711
[13291.785703] Internal error: Oops: 0000000096000021 [#1]  SMP
[13291.830975] Modules linked in: tls qrtr mana_ib ib_uverbs ib_core xt_owner xt_tcpudp xt_conntrack nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nft_compat nf_tables cfg80211 8021q garp mrp stp llc binfmt_misc joydev serio_raw nls_iso8859_1 hid_generic aes_ce_blk aes_ce_cipher polyval_ce ghash_ce sm4_ce_gcm sm4_ce_ccm sm4_ce sm4_ce_cipher hid_hyperv sm4 sm3_ce sha3_ce hv_netvsc hid vmgenid hyperv_keyboard hyperv_drm sch_fq_codel nvme_fabrics efi_pstore dm_multipath nfnetlink vsock_loopback vmw_vsock_virtio_transport_common hv_sock vmw_vsock_vmci_transport vmw_vmci vsock dmi_sysfs ip_tables x_tables autofs4
[13291.862630] CPU: 122 UID: 0 PID: 61796 Comm: kworker/122:2 Tainted: G        W           6.17.0-3013-azure #13-Ubuntu VOLUNTARY
[13291.869902] Tainted: [W]=WARN
[13291.871901] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 01/08/2026
[13291.878086] Workqueue: events mana_serv_func
[13291.880718] pstate: 62400005 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
[13291.884835] pc : mana_smc_poll_register+0x48/0xb0
[13291.887902] lr : mana_smc_setup_hwc+0x70/0x1c0
[13291.890493] sp : ffff8000ab79bbb0
[13291.892364] x29: ffff8000ab79bbb0 x28: ffff00410c8b5900 x27: ffff00410d630680
[13291.896252] x26: ffff004171f9fd80 x25: 000000016ed55000 x24: 000000017f37e000
[13291.899990] x23: 0000000000000000 x22: 000000016ed55000 x21: 0000000000000000
[13291.904497] x20: ffff8000a200001b x19: 0000000000004e20 x18: ffff8000a6183050
[13291.908308] x17: 0000000000000000 x16: 0000000000000000 x15: 000000000000000a
[13291.912542] x14: 0000000000000004 x13: 0000000000000000 x12: 0000000000000000
[13291.916298] x11: 0000000000000000 x10: 0000000000000001 x9 : ffffc45006af1bd8
[13291.920945] x8 : ffff000151129000 x7 : 0000000000000000 x6 : 0000000000000000
[13291.925293] x5 : 000000015f214000 x4 : 000000017217a000 x3 : 000000016ed50000
[13291.930436] x2 : 000000016ed55000 x1 : 0000000000000000 x0 : ffff8000a1ffffff
[13291.934342] Call trace:
[13291.935736]  mana_smc_poll_register+0x48/0xb0 (P)
[13291.938611]  mana_smc_setup_hwc+0x70/0x1c0
[13291.941113]  mana_hwc_create_channel+0x1a0/0x3a0
[13291.944283]  mana_gd_setup+0x16c/0x398
[13291.946584]  mana_gd_resume+0x24/0x70
[13291.948917]  mana_do_service+0x13c/0x1d0
[13291.951583]  mana_serv_func+0x34/0x68
[13291.953732]  process_one_work+0x168/0x3d0
[13291.956745]  worker_thread+0x2ac/0x480
[13291.959104]  kthread+0xf8/0x110
[13291.961026]  ret_from_fork+0x10/0x20
[13291.963560] Code: d2807d00 9417c551 71000673 54000220 (b9400281)
[13291.967299] ---[ end trace 0000000000000000 ]---

Disassembly of mana_smc_poll_register() around the crash site:

Disassembly of section .text:

00000000000047c8 <mana_smc_poll_register>:
    47c8: d503201f        nop
    47cc: d503201f        nop
    47d0: d503233f        paciasp
    47d4: f800865e        str     x30, [x18], #8
    47d8: a9bd7bfd        stp     x29, x30, [sp, #-48]!
    47dc: 910003fd        mov     x29, sp
    47e0: a90153f3        stp     x19, x20, [sp, #16]
    47e4: 91007014        add     x20, x0, #0x1c
    47e8: 5289c413        mov     w19, #0x4e20
    47ec: f90013f5        str     x21, [sp, #32]
    47f0: 12001c35        and     w21, w1, #0xff
    47f4: 14000008        b       4814 <mana_smc_poll_register+0x4c>
    47f8: 36f801e1  tbz  w1, #31, 4834 <mana_smc_poll_register+0x6c>
    47fc: 52800042        mov     w2, #0x2
    4800: d280fa01        mov     x1, #0x7d0
    4804: d2807d00        mov     x0, #0x3e8
    4808: 94000000        bl      0 <usleep_range_state>
    480c: 71000673        subs    w19, w19, #0x1
    4810: 54000200        b.eq    4850 <mana_smc_poll_register+0x88>
    4814: b9400281      ldr   w1, [x20] <-- **** CRASHED HERE *****
    4818: d50331bf        dmb     oshld
    481c: 2a0103e2        mov     w2, w1
    ...

From the crash signature x20 = ffff8000a200001b, this address
ends in 0x1b which is not 4-byte aligned, so the 'ldr w1, [x20]'
instruction (readl) triggers the arm64 alignment fault (FSC = 0x21).

The root cause is in mana_gd_init_vf_regs(), which computes:

  gc->shm_base = gc->bar0_va + mana_gd_r64(gc, GDMA_REG_SHM_OFFSET);

The offset is used without any validation.  The same problem exists
in mana_gd_init_pf_regs() for sriov_base_off and sriov_shm_off.

Fix this by validating all offsets before use:

- VF: check shm_off is within BAR0, properly aligned to 4 bytes
  (readl requirement), and leaves room for the full 256-bit
  (32-byte) SMC aperture.

- PF: check sriov_base_off is within BAR0, aligned to 8 bytes
  (readq requirement), and leaves room to safely read the
  sriov_shm_off register at sriov_base_off + GDMA_PF_REG_SHM_OFF.
  Then check sriov_shm_off leaves room for the full SMC aperture.
  All arithmetic uses subtraction rather than addition to avoid
  integer overflow on garbage values.

Define SMC_APERTURE_SIZE (32 bytes, derived from the 256-bit aperture
width)

Return -EPROTO on invalid values.  The existing recovery path in
mana_serv_reset() already handles -EPROTO by falling through to PCI
device rescan, giving the hardware another chance to present valid
register values after reset.

Fixes: 9bf66036d686 ("net: mana: Handle hardware recovery events when probing the device")
Signed-off-by: Dipayaan Roy <dipayanroy@linux.microsoft.com>
Link: https://patch.msgid.link/afQUMClyjmBVfD+u@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

0 files changed, 0 insertions, 0 deletions