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

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